The present disclosure provides a system and a method for calcining coal gangue, which belongs to the technical field of coal gangue treatment and resource utilization. The system for calcining coal gangue provided by the present disclosure includes a pretreatment system (1), a crusher (4), a screening system (5), an elevator (6-1), a screw feeder (6-2 ), a rotary kiln (7), and an exhaust gas treatment system (8). The crusher 4 includes a hammer crusher or an impact crusher. The screening system 5 includes a flip-flow screen or a vibrating screen. Both the flip-flow screen and the vibrating screen are of double-layer screen mesh structures. The mesh size of an upper-layer screen f a double-layer screen mesh structure is 25 mm, and the mesh size of a lower-layer screen of the double-layer screen mesh structure is 0.5 mm.