The invention provides an analog network coding system cooperative jamming method. A bidirectional relay channel communication system comprises information source nodes A and B, a relay R and an external eavesdropper E. Cooperative jamming carries out jamming on the information source nodes; a transmission mechanism of an analog network coding system finishes one bidirectional communication through two time slots; and under the condition that the transmitting power of the jamming signal is limited, by adjusting power distribution factors of the transmitting power of the jamming signal in each communication time slot, optimization of safety performance of the ANC system is realized. The method, on the basis that ANC can greatly enhance safety performance of a physical layer of the system, combines the CJ technology to further enhance the safety performance of the physical layer; the higher the transmitting power of the jamming signal is, the better the safety performance of the physical layer is; the method is suitable for the condition, where existing internal and external eavesdroppers exist simultaneously, and the transmitting power of the jamming signal is limited; and the method can reduce resource waste and realizes maximization of the safety performance.