[Objective] The rule of runoff formation in karst area was studied to get the parameters of space cooperation system(SCS) model and to test whether it is applicable in the study area.[Methods] Based on field observations of runoff and rainfall characteristics, rainfall events in the study area were classified. Runoff generated on the slopes was simulated by using the SCS model.[Results] (1) Rainfall events in the study area can be divided into four types according to event-based rainfall concentration, namely the pre-type(typeⅠ), medium-type(typeⅡ), back-type(typeⅢ) and even-type(typeⅣ). (2) The value of the initial loss coefficient(λ) was 0.01 or 0.05, much less than 0.2, when simulating runoff on the slopes in the study area by using the SCS model. (3) The curve number(CN) values of typeⅠ, typeⅡ and typeⅢ rainfall showed small changes as slop length increased, while the CN value of typeⅣrainfall tended to increase. The CN values of typeⅠand typeⅡrainfalls tended to reduce with the increase of slope gradient, the CN values of typeⅢ and typeⅣ rainfall did not increased obviously with the increase in slope gradient.[Conclusion] Based on SCS model, the correlation coefficient and model efficiency coefficient of simulated runoff and observed runoff are both high, which indicates the model performed well.