Abstract: With the development of the computing technology,the high performance/price ratio parallel computing,represented by the Message Passing Interface(MPI)standard,is applied widely to the more traditional professional fields. The massive computing is required since that the digital watershed model discussed in this paper is aimed to simulate the distributed hydrological and sediment process in a large-scale watershed. The parallel computing of the digital watershed model has its proper advantage including the cell partition mode based on the watershed division and the technical coding method of the drainage network. This paper presents a typical parallel scheduling flow to accomplish dynamically task assignment in rainfall-runoff and discharge routing computing. The application experiment on the MPI computing cluster constructed in this paper indicates that the cluster computing improves the computing efficiency of the digital watershed model. The paper presents the future development of this cluster computing flat as well.