In high-speed train (HST) communication, the application of 5G technology is of great importance. The massive multi-input multi-output (massive MIMO) technology in HST communication has advantages, but there are problems of inter-channel interference and multiple antennas synchronization. Spatial modulation has been widely used as a technology to solve this problem. In order to ensure the security of the HST wireless communication system, a hyperchaotic antenna-index spatial permutation modulation (HASPM) is proposed by combining chaos theory on the basis of spatial modulation technology. Aiming at the problem of reduced spectrum efficiency in traditional encryption algorithms due to pre-shared keys, channel information and noise interference, the proposed HASPM physical layer encryption scheme can improve above shortcomings on the basis of secure communication. The multipath fading effect is reduced, the bit error rate (BER) performance is greatly improved, and the system security and reliability are thus guaranteed. The evaluation results of calculation analysis and simulation on the scheme verified the feasibility and effectiveness of the proposed scheme.