Abstract: In the actual transmission of the wireless communication system, when the eavesdropping user is close enough to the legal receiver or is located on the radio wave path of the signal of the legitimate receiver, main channel and eavesdropping channel may be correlated with each other. To this end, we consider a wireless communication system with multiple inputs and single output, and a single antenna passive eavesdropper. We studied the impact of correlation on system performance when the base station uses the maximum ratio technology to transmit signals. The closed expressions of secrecy outage probability and average secrecy capacity are derived. Numerical simulation results show that (1) when the channel quality of the main channel is higher than the eavesdropping channel, the lower correlation has little effect on the performance of the system safety interrupt probability, but the strong correlation can improve the reliability of the system; (2) the correlation The average safety capacity is always harmful, and as the degree of correlation increases, the advantage of the maximum specific transmission technology over antenna selection gradually decreases.