Rainwater runoff has a significant impact on the environmental quality of urban scenic water bodies. Aiming at the sediment load pollution of rainwater runoff in Nanhu Lake, Yuncheng County, Shandong Province, a hydrocyclone experiment was carried out in laboratory to study the removal effect of the suspended solids and its influencing factors in the initial rainwater runoff. The results show that the separation efficiency of the hydrocyclone decreases with the increase of the feed concentration but increases with the increase of the feed flow. According to the test results, the regression relationship between the separation efficiency, feed concentration and feed flow of a certain kind of hydrocylone was fitted. Based on the actual situation of Nanhu Lake, the separation efficiency of this hydrocyclone on suspended solids is estimated to be about 26.63%, so it is necessary to combine multi stage hydrocyclones or take other treatment measures to make the inflow runoff of the lake reach the preset standard.