According to river drainage standard of Changzhou city and Under the condition of typical rainstorm ,the runoff process of Shuangqiaobang area was simulated based on SCS model . The variation process of water level in pump station is also simulated under the condition of different drainage capabilities. Simulation results show that the existing drainage capability of Shuangqiaobang pump station is low and can't meet the requirements of the region's flood control and waterlogged. The suitable scale of drainage is 5.00 m3/s.