Free-space optical communication (FSOC),which features the large capacity,high data transmission rate,high anti-EM interference capability,good security,low power consumption,small dimension and simple structure,is the tendency of the communication between ships in the future. This paper studies the simulated moving platform of the ship-borne laser communications system,which mainly consists of four parts:a horizontal,a vertical,a rotating and a swing moving platforms,simulating ship′s four swaying motions in wave:surge,heave,roll and yaw respectively. According to the ship motion equations,we mainly discuss the motion law of the ship in the wind waves by using linear system theory. These four movements can be used to synthesize ship′s complex movements in waves,and thus could simulate ship′s movements in various sea conditions in laboratory,providing a simulation experimental environment for studying the ship-borne laser communications system. The manipulation and control of the platform are realized through computer.