In order to provide basic data for initial rainfall interception control, the first flush effect of non-point source pollution in Guangzhou community unit was studied in this paper. The runoff pollutants at road, roof and greenbelt during three rainfall events in the study area were collected and analyzed. The dimensionless cumulative curve, the first flush coefficient and MFF index were used respectively to do quantitative analysis and qualitative analysis of the first flush effect of runoff pollutants such as BOD₅, COD_Cr, TSS, NH₃-N, TP and TN. The results showed that the first flush at greenbelt and roof occurred more easily and had more intensity than that at road, and the first flush at greenbelt is more obvious after successive rains. Among the various pollutants in the first flush, the first flush effect of TN is more obvious, and TP and NH₃-N take the second place. The more reliable quantitative results can be obtained by the MFF index method, and it is recommended to be the analysis method of the first flush effect.