As a new clean energy, natural gas hydrate (combustible ice) has attracted worldwide attention. The second round of trial production of natural gas hydrate in China Sea area organized and implemented by China Geological Survey has achieved success and exceeded the target task. At present, although the development of natural gas hydrate simulators at home and abroad and related researches describe the behavior of "sand" through mechanical coupling, But most of them do not involve the flow process of "sand". Aiming at the numerical simulation of the "sand" flow process in the porous media of the reservoir after the decomposition of natural gas hydrate, the general-purpose subsurface flow simulator GPSFLOW was used to realize the three-phase three-component simulation of water, gas (methane), and sand. The sand was regarded as a non-Newtonian fluid: one component and one phase, and the simulation was performed according to Bingham fluid. The theoretical method and model realization scheme of sand flow process simulation are discussed preliminarily, and verified by ideal model. The results show that compared with other sand production numerical simulation research methods, the sand flow simulation method proposed is simple and efficient, and can effectively simulate the sand flow process. It is expected to realize the accurate simulation of sand flow in the process of hydrate production by coupling the seepage model of hydrate production.