Because SWMM(storm water management model)does not consider the purification effect of LID(low impact development)measures in pollutant simulation, there is a big error in calculating the annual total removal rate of SS. In order to compensate for this error, a method for calculating the total removal rate of SS based on SWMM and considering the purification effect of LID measures was proposed. Taking Yutian River Basin in Shenzhen City as an example, SWMM was constructed. The results show that the total removal rate of SS is 23. 2% without considering the purification effect of LID measures, 30. 1% with considering the purification effect of LID measures, and the latter is 1. 3 times the former. Meanwhile, the conceptual differences between annual total runoff control rate and annual total removal rate of SS are discussed. It is pointed out that there is no definite proportional relationship between them. The total removal rate of SS in typical plots may be higher than the annual total runoff control rate when the initial rainfall scouring effect is considered and the LID measures mainly intercept early small and medium rainfall.