In order to study the influence of rainfall data with different time step accuracy on the total quantity control rate of annual runoff in sponge city simulation evaluation calculation, the InfoWorks ICM hydraulic model software is used to build the sponge city evaluation hydraulic model of a campus in the southeast coast, and the simulation evaluation of the total quantity control rate of annual runoff under 11 working conditions with different time step accuracy of 5 min~1 d is carried out. The results show that with the decrease of rainfall data accuracy, the relative error of annual runoff volume control rate model shows an increasing trend. Compared with the simulation results of the precision of rainfall data every 5 min, the relative error of annual runoff volume control rate within the precision range of 10 min~1 h time step is smaller. In this range, the relative error is the largest by 1h step, but only 0.64%. The relative error of the calculation is in the middle level of 3.13% ~9.23% when the time step is 3 h~6 h. The relative error of each 12 h~1 d time step is the largest, which is up to 12.03%. Therefore, when calculating and evaluating the annual runoff volume control rate model of sponge cities in the southeast coastal area, at a minimum, hour-by-hour accuracy of rainfall data is required.