Improving confidentiality is a major issue in many wireless transmission systems. Physical layer security techniques are often used to improve confidentiality from eavesdroppers. In this paper, we propose a secure communication method based on physical layer encryption to ensure the security of transmitted data. We adjust the modulation method and phase of the transmitted signal based on the conventional encrypted signal. The adjustment is jointly determined by the encryption key and the front-end signaling information. The proposed method has almost no bit error rate (BER) performance loss under different signal-to-noise ratios (SNR) compared to conventional communication methods. While, the method can realize eavesdropping-proof high-security communication with low complexity.