In order to achieve the quantitative calculation of stormwater control in the construction of Sponge city, it would require a large number of data base with model simulation, which is hard for extension. This paper takes runoff coefficient as the main analysis means, using a simple method to calculate the stormwater control indicators of Chengdu living water park before and after the transformation to sponge park.The rain type of Chicago was used to distribute the rainfall that occurs every five years. Through analysis and comparison of discharge in the park that before and after the transformation, it shows that the effluent water flow peak clipping rate was 74%, and the peak delayed 25 min after transformation. The runoff coefficient is 0.278, and the volume capture ratio of annual rainfall is more than 85%. The control of stormwater is efficient for the rainfall that occurs every five years and every three years. This calculation method of stormwater control can be used in small type pilot area or sponge city park, which requires small amount of data has high maneuverability, repeatability and high application value. It can provide certain reference for the calculation of stormwater control indicators in the construction of Sponge city.