A screen film structure with a magnet assembly is used on a screen having a rim. The screen film structure includes a screen film and a magnet assembly. The magnet assembly includes a first magnet element and a second magnet element. The first magnet element is attached to the rim. The second magnet element is attached to the screen film. The first magnet element and the second magnet element are magnetically attracted to each other to arrange the screen film to cover the screen. Accordingly, it is easy and convenient to attach and detach the screen film structure, and the screen film is fastened firmly to the rim.