Abstract: In this paper the effect of nitrogen fertilizer use on the soil and ground water pollution was studied through the field servey and field experiments in three agro-ecological regions in Shaanxi Province. The tesuits showed that a large amount of NO3-N has been accumulated in 0~4m soil profile and moved down to the ground water and surface water, which were polluted to different extent in some places due to more nitrogen frtilizer was applied. The amount and depth of NO3-N leakage during one crop season related to the application rates of N- fertilizer. techniques of fertilization, amount of received water and soil texture. Adopting the optimum rate of N fertilizer, balanced fertilization, optimum rate of irrigation water are important practices for minimizing NO3-N leakage, imporving N use efficieney and preventing the environment from pollution.