In order to grasp the diachronic variation law of the underlying surface pollutants, taking a university in Nanchang City as the research area, this study selecled the main road of the school, the main road of the student dormitory area, the leisure square of the school and the roof of the student dormitory as the four underlying surfaces. For a single rainfall event, it analyzed the variation of SS, COD, TN and TP pollutants on different underlying surfaces with rainfall time to understand the variation process of pollutants with rainfall duration. The results show that the water quality variation range and variation rules of different underlying surfaces and different rainfall events are different, the concentration of pollutants in rainfall runoff is generally attenuating, and the attenuation rate is relatively fast in the early stage and relatively flat in the later stage; The main pollutants in rainfall runoff of four different underlying surfaces are analyzed.