A composite rigid suspension system comprises a main spring, a first auxiliary spring and a second auxiliary spring, wherein both the main spring and the first auxiliary spring are connected with a frame web surface, the first auxiliary spring is located above the main spring, the main spring and the first auxiliary spring are connected with a rear axle through U-shaped bolts, the second auxiliary spring is connected with the lower web surface of a frame, the lower web surface of the frame is vertically connected with the frame web surface, and the second auxiliary spring is located above the rear axle and is located on the right side of the main spring and the first auxiliary spring.The composite rigid suspension system is good in smoothness and high in reliability.