Taking the semi-karst region of Guizhou Province as the research object, the characteristics of surface runoff with different rainfall intensity were analyzed through artificial rainfall experiment, and the experimental results showed that：at any time during the rainfall, the greater the rainfall intensity is, the greater the surface runoff is. During the rainfall, when the rainfall intensity is 30mm/h, the runoff coefficient ranges from 0.0143 to 0.0407. When the rainfall intensity becomes 75mm/h, the runoff coefficient range is 0.0093~0.0420. While the rainfall intensity is 120mm/h, the ranger of runoff coefficient is 0.0093~0.0420. The change of erosion and sediment with rainfall over time is larger than the surface runoff. The variation curve of sediment concentration shows obvious irregular fluctuation. When the rainfall intensity is 30mm/h, the runoff time is 2.37min, when the rainfall intensity is 75mm/h, the runoff time is 1.29min, when the rainfall intensity becomes 120mm/h, the runoff time is 1.51min. At the end of the rainfall, the cumulative surface runoff expressed as the greater the rainfall intensity is, the greater the cumulative surface runoff is, and when the rainfall intensity is 120mm/h, the cumulative surface runoff is the largest. The runoff coefficient calculated from the cumulative surface runoff is gradually reduced with the increase of the rainfall intensity. The research indicates that, in the semi-karst area, different rainfall intensity makes different characteristics of surface runoff. This experimental results can provide some theoretical reference for Soil and Water Conservation and Ecological protection construction in the semi-karst area.