A pet gear assembly includes at least two main boards, a plurality of supporting posts, and a plurality of side boards. A plurality of through holes are formed in each of the at least two main boards. The plurality of supporting posts are disposed between and perpendicular to the at least two main boards, and two ends of each of the supporting posts respectively pass through each of the through holes. The plurality of side boards are respectively disposed in a frame-shaped area defined by two adjacent ones of the supporting posts and two of the main boards. The at least two main boards, the plurality of supporting posts, and the plurality of side boards jointly form a box unit, and at least one opening is formed in one of the side boards to allow a pet to enter or exit.
