In order to realize the secure communication of physical layer in any desired direction in free space, a directional modulation method is proposed based on multiobjective function genetic simulated annealing algorithm. In this paper, two genetic objective functions are established based on the BER performance of communication signals and the degree of constellation distortion in combination with simulated annealing algorithm to avoid genetic algorithm from falling into local optimum. The transmitted signal is the same as the expected constellation in the legal user direction, while the constellation map in the eavesdropping user direction produces a great degree of distortion. The simulation results show that the directional modulation method proposed is narrower in BER beam width compared with the existing directional modulation methods, genetic algorithm, particle swarm algorithm and multiobjective genetic algorithm. The proposed multitarget directional modulation physical layer secure communication signal has stronger antieavesdropping performance.