In this paper, a composite heterostructure mesh-shaped patch antenna based on left handed material (LHM) is presented. The method of finite difference time domain (FDTD) is used. The results show that electromagnetic wave resonance occurs near 4.52 GHz, where the equivalent permittivity and permeability of composite material are both negative. The composite antenna’s gain improves 9.047 dB, its return loss reduces 20.26 dB compared to the conventional antenna’s ones. The results indicate that this composite patch antenna system can reduce return loss of the antenna and increase the gain obviously.