The invention relates to the technical field of plate turnover in the composite plate machining, in particular to a plate turnover machine. The plate turnover machine comprises a first turnover mechanism and a second turnover mechanism which are completely same in structure, and the spacing distance between the first turnover mechanism and the second turnover mechanism along a carrier roller frame is smaller than the length of a plate to be turned over and larger than 1/2 of the length of the plate to be turned over. According to the machine, the problems that an existing plate turnover machine is heavy, gear transmission is affected by factors of the work condition, the speed, the load, the material heat treatment and the like, gear breaking, corrosive pitting, gear face wear and the like can appear, and the noise pollution caused by equipment damage, the motor roaring and gear friction is generated are solved.