The traditional lunar simulator have characteristics shortcomings of complex design principles, high cost and poor radiation. In this article, we apply liquid crystal light valve technology to design a new lunar simulator, and focus on the light source of lunar simulator. Application of liquid crystal on silicon (LCOS) optical splicing technology effectively improves the accuracy and simulation capabilities of lunar simulator. Through the control program to adjust LCOS pixel voltage, LCOS modulates the incident light into different states, so it can simulate different radiation characteristics and phases. Simulation results show that: the design of the light source simulated by lunar simulate can simulate the phase diversity, and uneven brightness is good. Using LCOS device simulator effectively improves the control precision, rednces the volume of the simulator compared with the traditional simulator.