Abstract: Subaqueous landslides are one of the common natural disasters. PFC is difficult to simulate the subaqueous fluid environment. In order to solve this problem, a calculation method using computational fluid dynamics OpenFOAM and PFC is proposed. Aiming at the problem of scale similarity in fluid-solid coupling, a similarity method suitable for this coupling method is proposed and its feasibility is verified. The dynamic characteristics and accumulation morphology of subaqueous landslides based on the coupling method are analyzed through typical cases, and compared with the results of unidirectional coupled subaqueous landslides and upland landslides. The results show that the coupling method can simulate the law of subaqueous landslide movement well, which mainly shows that the front end of the landslide body is thick and elliptical. Subaqueous landslide movement process and accumulation form are quite different from the landslides on land. The OpenFOAM-PFC bidirectional coupling method is superior to unidirectional coupling method.