The first scene of the film starts with the antagonists, an old man ruling over a nomadic tribe who terrorized season after season the Chinese people. The old leader is ready to return to his homeland and take a break from stealing but his oldest son has other ideas. The oldest son is named Mendu and when his father finds him, he tries to convince the rest of the elders the time has come to take over the fertile lands owned by the Emperors. It is unsure whether the son convinced the elders of not but the scene then changes.
In the second scene, an old man sits in a village square surrounded by men. From their conversation it is clear they are all former soldiers, thinking about what they experienced on the battlefield. Mulan is also introduced here, as Hua Hu's single child, a rebellious daughter who does not want to listen to the way society tells her to behave. In the same scene, three soldiers come, calling each man by name and telling them they are to go on the battlefield.
Despite his age, Hua Hu is among the men called to go to war. That night, he prepares himself and his armor, while Mulan watches from afar. That night, Mulan decides to take her father's place. Through a series of flashbacks, the viewer finds how Mulan was always put down and criticized because she did not behave as a girl should have. This makes her even more determined to go and prove her worth.
When Mulan reaches the camp, she is recognized by a childhood friend named Tiger. She quickly makes new friends, among which the sub- commander's son, a man named Wentai. Mulan proves her worth by training hard and not causing any form of trouble. Still, she fears constantly for her life, knowing she could be executed if the battalion were to find out she was a girl.
Mulan's secret is almost discovered one night when Wentai sees her taking a bath in a nearby hot-spring. Mulan manages to avoid being seen and returns to the camp where she tells Tiger about what had taken place. Tiger tells her not to worry about it but the next morning another problem arises, when the commander's nephew comes to the tent, were Mulan was staying and claiming someone inside the tent stole from a pendant. The commander orders everyone in the tent to strip so they could be searched, puting Mulan in a very dangerous situation.
Mulan realizes she will killed no matter what so she decides to claim she was the one who stole the pendant. By doing this, she hopes she can avoid being discovered as a woman and avoiding bringing shame to her family name. That night, Mulan is visited by Wentain and she confesses everything to him. She also pleads with him to lie to her father and tell him she died in battle, something he agrees to.
The next day, Mulan is woken up by the sound of battle. The camp is attacked by the Rouran and Wentai comes to set Mulan free, telling her to run. Mulan returns to fight and she is the one who kills the Rouran commander. Unfortunately, the battalion's commander is also killed in battle. After the battle is done, Mulan is offered the position fo second in command by Wentai.
Mulan and Wentai both advances in their positions and they are decorated time and time again. Mulan has to see her friends killed one by one, their deaths affecting her more and more with each passing day.
One day, Mulan makes the decision to disobey Wentai's orders and to go after him when she hears he and his troops have been ambushed. Mulan leaves behind her men, who are then ambushed and many of them killed.
Shortly after, Wentai is killed on the battlefield as well, his nametag reaching her through Tiger who was fighting alongside him. Mulan falls into a deep depression, refusing to train her troops anymore. Tiger makes her see the truth in the end and she takes over the role of general.
The next scene shows how Wentai was not killed but was only wounded. Wentai told the Tiger to pretend he was killed so Mulan could have the opportunity to become a better commander. Meanwhile, Mulan wins battle after battle, winning the respect of her troops and also the fear of her enemies.
Unfortunately, the Commander Supreme grows jealous of Mulan, and orders her to be made once more a simple soldier. The enemy commander is also enranged, with the younger son taking over the command. When the heads of the other tribes claim they wanted to return home, Mendu kills one of them to stop them from giving up. Mendu then kills his own father, in order to take command of the tribes.
The generals get wind of Mendu's plans and Mulan comes up with a plan to defeat them which is supported by the other generals and by Supreme Commander. Mulan and her men fight bravely but many are wounded and even killed. Wentai reveals himself during the battle and helps Mulan, who was wounded, to get back to the camp. Unfortunately, Tiger remains behind in an attempt to try and stop the enemies.
Mulan and the rest of her soldiers find safety in a cannon but none of their supplies are there, meaning the Supreme Commander failed to do what he promised to do. Mendu refuses to kill the soldiers, preferring to wait for them to die of starvation and hunger, thus proving once more his cruelty.
The soldiers remain in the canyon for days, with Wentain taking care of Mulan and confessing his feelings for her as well as his fear she will die. One morning, Mulan and the other soldiers go at the entrance of the canyon to see their fellow soldiers, the ones who were captured, being beaten and killed in front of them. Among them is Tiger and Turtle tries to run to help him, only to be killed by the enemy. While Mulan and the rest are watching, the captured soldiers are all killed one by one, making Mulan realize she can no longer wait for help and must act on her own, realizing the other generals have betrayed her.
Wentai, in an attempt to save Mulan, reveals his true identity, that of the Emperor's seventh son and agrees to go quietly as a prisoner as long as Mulan and her troops are let free and taken care of. Mulan does not give up on him, but rather dresses as a woman once more and snuck into the Rouran camp where she snuck in the middle of the night to talk with Mendu's sister and they both come up with a plan to save their people.
Mulan tells the princess she has more power than she believes and convinces her not to give up. During a feast, Mulan and Mendu's sister put their plan into motion, killing Mendu. Through a flashback, it is revealed that Mulan went to the emperor to tell him the truth and then returns home to see her father. It is also revealed Mulan was away for 12 years, fighting on the battlefield for the Emperor. It is also shown how after Wentai was saved, he married the Rouran princess in an effort to stop the two nations from fighting.
Mulan returns home but not long after she is visited by Wentai, who tells her he loves her and wants to be with her. Mulan refuses, knowing his duty is to marry a princess, not a common girl. In this sense, Mulan puts the duty she has for her country above her personal feelings, choosing to do what is better for her country. The film ends with Wentai and Mulan departing from one another, never to see each other again.
