what attracts winston to julia.why would she be attracted o him?

Julia was simply young and attractive.Winston finds Julia to be a rebel against the party which attracts him further to her.

It is in part 2, chapter 2 that Julia and Winston get together alone for the first time and they get to talk freely with one another. Winston asks Julia why she would be attracted to him. She responds that it was something in his face. She goes on to tell him that she is good at "spotting people who don't belong", or fit in with the Party and the general attitude of the masses. She tells Winston that she could tell by looking at him that he was against the Party.