Abstract: Based on triangular grids,the planar 2-D flow and sediment mathematical model is established by the finite element method Since the mass concentration and the pre-estimated and verified iteration are used to solve the equations,the questions of memory units and calculation velocity are settled quite well Simulation calculation is carried out on the cavity recirculation and single-sudden-expansion channel The results show that flow field and sediment distribution are simulated successfuly in the model and the calculations are stable,fast and accurate