In order to improve the security of wireless communication system transmission, a scheme of Reconfigure Intelligent Surface (RIS) assisted Generalized Spatial Modulation (GSM) is proposed to realize Physical Layer Security (PLS) transmission. Firstly, after the signal is transmitted from the transmitter, the RIS reflection unit is grouped, and then different RIS reflection unit groups are activated by GSM to reflect the signal to the receiver. At the same time, artificial noise (AN) is added to the transmitted signal to expand the channel difference between legitimate users and eavesdroppers. Reduce information leakage and ensure transmission security. In addition, this scheme realizes GSM transmission of additional index bits through RIS cooperation, which can effectively improve the transmission efficiency of the system. Finally, the theoretical analysis and experimental simulation of the system bit error rate and secrecy rate are carried out. The results show that the scheme can not only reduce the bit error rate of the legitimate receiver, but also effectively improve the security of the system transmission. Compared with traditional schemes, when the bit error rate is negative cubic of 10, the SNR has a performance gain of about 2.2 dB. When the SNR is 20 dB, the average secrecy rate is increased by about 200%.