Sichuan University’s job fair on October 17th can only be attended by our school?

Of course not. Anyone with a ticket can enter, but tickets are usually issued to your own school. How to get them, you have to figure out how to get them.

The University of Electronic Science and Technology of China is not the same day, of course it is different, and the units you come to are also different. I suggest you go and see them all, at least you will gain some insights! !