Abstract: To improve the security of directional modulation at physical layer, two kinds of directional modulation signals are designed based on the optimization of static excitation and dynamic excitation. Under the constraint of transmitter efficiency, the optimization model is measured by eavesdropper’s symbol error rate for static excitation and amplitude attenuation for dynamic excitation in a certain areas. Then the model is optimized with augmented Lagrangian genetic algorithm. Simulation results show that, compared with general directional modulation signal under the same transmitter efficiency, the optimized signal can further improve the symbol error rate of eavesdroppers and owns a better security performance.