I don't know him, never talked to him, but both of us knows the existence of the other from a university we both study in. I always notice him and he notices me when we pass by each other but we both look away (and even try to ignore each other) quickly after.

(I look away and try to ignore him 'cause I've had a stupid, annoying crush on him I'd rather be without). My question is, why is HE looking away quickly too? Does he hate me? What's going on his mind?

HMM THIS IS WODERFUL.. he's not looking away because he hates you he's looking away because he has feelings for you to. Next time you pass him in the hallway look him directly in the eyes smile like youv'e never smiled before and just say "hey" or "hi" so that he knows that you feel the same way

If you have a crush you don't want,why does it bother you if he looks away or not?

Do you want something to happen?

Maybe he's shy or feels the same way.
A crush he does not want.

Nobody knows what is running through his head, he only knows.

It seems like the two of you have awkward moments and maybe a liking for one another but no one is saying anything or doing anything about it.

First, do you know if he is single?

Secondly, if he is not involve with someone then you have the option to either step up and say something or continue looking at each other in passing. The choice is yours but keep in mind "nothing venture is nothing gained".