Network Coding - This paper proposes a hybrid encryption scheme for multi-relay (MR) physical-layer network coding (PNC). Based on the three-relay (3R) bidirectional communication model, first, we discuss the throughput performance of the PNC compared with the traditional scheme (TS) and network coding (NC) system. Through the analysis of transmission efficiency, the superior throughput of the PNC system is demonstrated. Then, to further improve the security of the communication system, we give a scheme of advanced encryption standard (AES) and RivestShamir-Adleman (RSA) hybrid encryption, namely AR hybrid encryption. Finally, we embed the AR hybrid encryption into the multi-relay PNC communication system. At relay nodes of the ARPNC system, we focus on solving the problem of signal mapping. In the meantime, to reduce the performance loss caused by the increase of relay nodes, we exploit Low-Density Parity-Check (LDPC) code to enhance the decoding accuracy. The experimental results and security analysis show that the proposed scheme can boost the system throughput and transmission dependability and stronger the security of the communication system.