Abstract: Rice is broadly planted in China. Ammonia volatilization, nitrogen (N) and phosphorus (P) runoff and leakage have caused agricultural non-point source pollution and other issues due to excessive fertilization. The concentration of N and P in surface water during the flooding period is the key control factor. The dynamic characteristics of N and P in surface water of paddy field and their potential environmental impact were studied by field experiment with different P and N application. The results show that the concentration of total P (TP), total dissolved P (TDP) and particulate P (PP) all increased rapidly within 9 days after P application and then decreased. The concentrations of TP, TDP, and PP reached 0.76, 0.71 and 0.03 mg·L^-1 with 214 and 90 kg·hm^-2 N and P application, respectively. Besides, the concentration of TP and TDP showed an obvious rise after the soil-drying period. The concentration of ammonium nitrogen and nitrate in all treatments reached to maximum in 2 and 5 days, respectively, after the application of basal fertilizer. The concentration of ammonium nitrogen with 214,182 and 162 kg·hm^-2 of N application were 15.83, 9.16 and 7.86 times of that in control treatment. N concentration decreased rapidly after 5 days and the differences between treatments became much smaller. In addition, increasing N and P application amount did not significantly increase the rice yield, but inversely, rice yield decreased with 214 and 90 kg·hm^-2 of N and P application, respectively. Therefore, 9 days after P application and the stage after rewetting were the key periods for controlling P losses through runoff in surface water from paddy field, while 5 days following N application is the vital period for controlling N losses. By considering both rice yield and fertilizer agronomic efficiency, it is feasible to reduce 25% of N and P application. However, this should be further investigated for high yield consistency through field experiment.