Abstract: Using multiple transmit antennas to guarantee the information security is one of the common methods in the field of physical layer security communication. However, this method leads to the transmit signal with the drawback of high Peak-to-Average Power Ratio (PAPR), which degrades the communication performance for the desired receiver. In this paper, the PAPR conception for security communication signal based on the weighted antenna array is defined from the point view of weighted value. The degradation performance of the desired receiver is also analyzed. In addition, a PAPR reduction algorithm is proposed for the physical layer security communication system using a random antenna array. Simulation results show that the proposed algorithm reduces the PAPR value for the security communication signal under the condition that the security performance does not reduce.