Directional modulation (DM), as the key technology of wireless physical layer security transmission, can improve the secrecy performance of the system. However, due to the angle measurement error, we need to consider the angle error to improve system security performance when designing useful signal beamforming vector and artificial noise (AN) projection matrix. The paper first describes system model of DM. Then we introduce the direction of arrival (DOA) estimation technique, three algorithms of robust beamforming design and power allocation technology. Simulations show that the performance of the robust beamforming synthesis method is obviously better than that of the non-robust synthesis method, and the optimal power allocation between the confidential information and the AN can significantly improve the security rate performance. Finally, the future new research directions and challenging problems are presented.