In this paper, a spaceborne oceanic lidar simulation system used semianalytic Monte Carlo method was developed. The system can simulate the lidar returns of the atmosphere and the ocean with different optical properties through entering the parameters of the lidar system and the environmental parameters. At the same time, a user-friendly software interface for users was designed to operate input parameters and observe the output results intuitively. A variety of simulations was done, such as different types of water and different scattering phase functions. The simulation results were highly consistent with the theoretical lidar equations. The system was important to the research on the detection mechanism of spaceborne oceanic lidars.