In view of an inquiry into the reduction effect of grass planting ditches on rainfall runoff pollution, a demonstration site for the grass-swale has thus been established on the campus green belt section. Based on the findings of the overall rainfall water quality and rainfall runoff characteristics of different underlying surfaces on the campus, a further study is conducted on the control effect of the grass-swale on pollutants in roof rainwater and surface runoff. The results show that the COD and NH3-N concentrations in the campus rainfall runoff are high and need to be controlled. Moreover, the roof rainwater is more seriously polluted than the road runoff, possibly due to the release of organic matter in asphalt felt roofing materials, which increases the degree of organic matter pollution in runoff water. The initial pollution of roof rainwater during rainfall is relatively severe, while the concentrations of various pollutants in roof rainwater and road runoff decreases gradually, showing a tendency to stabilize with the rainfall duration. The removal rates of COD, turbidity, TP, and NH3-N from roof rainwater by the grass-swale are 59% to 98%, 50% to 83%, 59% to 93%, and 49% to 88%, respectively. It can be seen that the permeable ecological grass-swale, as a kind of vegetated ecological drainage ditch, helps to reduce the degree of coverage of impervious subsurface, thus verifying its effectiveness in controlling the urban surface pollution.