To improve the communication security performance of directional modulation for array antenna, a kind of combinatorial interference directional modulation method is proposed in this paper. Static interference and dynamic interference is combined to be the combinatorial interference. An optimization model with a measurement with a certain areas of bit error rate is made. Then the optimization problem is solved based on genetic algorithm. Simulation results are presented and showed that, compared with general directional modulation signal under the same transmitter power consumption, the combinatorial interference directional modulation signal is able to provide a wider safe area and has a better performance.