In order to explore the process of nitrogen emission from paddy field after rainstorm, a field experiment was conducted at Chuanhang irrigation district, located in Suqian, Jiangsu Province. The concentration of NH+4—N and NO-3—N, paddy drainage were measured at conventional and controlled irrigation and drainage mode. And the DRAINMOD-N II mode was used to simulate the drainage load of paddy fields, NH+4—N and NO-3—N loss after rainstorm. Measured results show that：controlled irrigation and drainage mode can significantly reduce paddy field drainage and nitrogen emission after rainstorm. The relative error RE between the simulated and measured values of drainage after rain using the DRAINMOD-N II model is less than 2%, the correlation coefficient R is above 0.98, and the simulation efficiency NS is more than 0.96. The relative error RE between the simulated and measured values of NH+4—N and NO-3—N is less than 5%, the correlation coefficient R is above 0.95, and the simulation efficiency NS is more than 0.90. Therefore, the parameters obtained by model calibration are more reasonable, and the DRAINMOD-N II model can be used to predict the drainage after rainstorm, NH+4—N and NO-3—N loss in the future.