A package box for containing an object and being turned inside out to form a pet kit includes: a bottom panel； four lateral panels integrally formed with the bottom panel； a top panel coupled to the lateral panels by joint structures, wherein the bottom panel and the lateral panels together define a receiving space for receiving the object, and the top panel caps the receiving space； and a cat scratching pad fixedly disposed on the back of one lateral panel and penetrated by a geometric hole. A geometric perforation corresponding in shape to the geometric hole is formed on two opposite lateral panels. Users unfold the package box and then fold it inside out to form a pet kit, expose the cat scratching pad, and remove a plate from within the geometric perforation, such that the pet kit is equipped with a cat maze playground and the cat scratching pad.
