Is the campus job fair an on-site written interview or just an interview notice such as resume?

Campus recruitment is relatively simple, not particularly strict. Generally, you bring your resume, and the interview manager will look at your resume and interview you on the spot to get to know you initially. If you have a good impression, you will be notified to reply.

Some companies don't need your resume. They have their own resume templates. When you go, they will give you a resume of their company for you to fill out on the spot.

In short, it is relatively simple, so don't be too nervous!