The effects of different nitrogen application modes on the variation of nitrogen concentrations in paddy field surface water and rice yield were analyzed, through constructing six nitrogen application modes with different fertilizer types, fertilizer amounts, fertilization modes and times. The results showed that after slow-controlled fertilization and urea application, the concentration of total nitrogen and ammonuim reached peak in 1 day, and the concentration of nitrate reached peak in 2~3 days, and then gradually decreased to a stable level. Ammonium nitrogen was the main form of nitrogen in the initial stage after fertilization, and the proportaion of ammonium nitrogen in total nitrogen concentration reached 50.6%~92.8% in 1 day, while nitrate nitrogen only accounted for 3.8%~22.6%. The peak concentration of total nitrogen and ammonium nitrogen in surface water was correlated with fertilizer type, fertilizer amount and fertilization mode. Under the condition of equal nitrogen fertilization, the order of peak concentration of total nitrogen and ammonium nitrogen in surface water was as follows:Spraying urea treatment > spraying slow-release fertilizer treatment > side-deep application of slow-release fertilizer treatment. Under 48 kg/hm² N fertilization condition, the average peak concentrations of total nitrogen and ammonium nitrogen in the treatments of spraying urea, spraying slow-release fertilizer, and side-deep application of slow-release fertilizer were 38.44, 16.44, 7.55 mg/L, and 34.39, 13.00 and 3.82 mg/L, respectively. Under the same amount of nitrogen application and times of fertilization, the yields of treatments 4, 5, and 6 with side-deep slow-release fertilizer were 2.8%, 3.5%, and 2.7% higher than those of treatments 1, 2 and 3 with corresponding spraying slow-release fertilizer, respectively. Under the condition that the total amount of nitrogen fertilizer was reduced by 30%, the yield of rice of treatment 6 with side-deep application of slow-release fertilizer during base fertilizer period and two-times fertilization only decreased by 0.3% compared with that treatment 1 with spraying slow-release fertilizer during base fertilizer period and three-times fertilization. The results showed that side deep application of slow-release fertilizer could effectively reduce the peak concentration of ammonium nitrogen in surface water at the initial stage of fertilization, thus reducing the risk of ammonia volatilization and runoff loss, and would not affect rice yield under certain reduction conditions.