With the rapid development of terahertz technology and its application, the demand for various kinds of terahertz manipulation devices increases as one of the important components of the terahertz system, the terahertz wave phase shifter has become a research hotspot. The reported terahertz wave phase shifters have large size, complex structure and small phase shift problems. In order to overcome the above defects, we proposed a novel terahertz phase shifter based on a grating liquid crystal composite structure. It is composed of quartz layer, graphene layer, liquid crystal cell, grating structure, graphene layer and quartz layer. By changing the voltage on graphene, the refractive index of the liquid crystal can be varied, and the phase of the proposed terahertz phase shifter will change due to the change of refractive index. Then, the phase shift of the proposed terahertz wave phase shifter can be effectively adjusted by controlling the externally applied voltage. The simulation results show that the phase shifter achieves 400° phase shift in the frequency range from 0.39 to 0.46 THz, and the return loss is less than -11 dB. The maximum phase shift is 422° at a frequency of 0.43 THz. When the incident angle of the terahertz wave varies from 0 ° to 30 °, the phase shift of the proposed phase shifter remains unchanged. In addition, the device is insensitive to the polarization state of the incident terahertz wave. The designed terahertz phase shifter has the advantages of a large phase shift and small structure size. It has widespread applications prospects in the future terahertz communication, security inspection, medical, sensing, imaging, etc.