Variation characters of nitrogen and phosphorus in the rice field and its pollution-reducing potential Were researched, Using controlled drainage technique in the micro-zone simulated paddy field with the water depth of 5,10 and 20 cm(expressed as t-5，t-10，t-20，respectively). Concentration of TN, NH4+-N and TP turned low with the water depth in the field, and showed a significant correlation between them (TN: y=－2.18x+10.87, R2=0.960; NH4+-N: y=－0.048x +2.063, R2=0.999; TP: y=－0.05x+0.223, R2=0.949). NO3－-N concentration in the t-20 treatment was higher than that in the t-5 and t-10 treatment, and increased at 5 d after deep application of fertilizer. However, there was not a obvious correlation between NO3－-N concentration and water depth in the field. Urea caused the lowest SS concentration to appear at 2 d after application because of its flocculation and sedimentation to the suspended particulates. During heavy rain frequent-occurrence period, drainage weir should be increased by 10~20 cm to extend the water logging time 5~7 d longer to reach the best pollution-reducing potential.