An in-situ observing experiment was carried to understand the effect of N application on N leaching of various depth of soil during different period of rice growth. The results showed 1) rice tillering stage had relatively higher averaged concentration of ammonium nitrogen (NH4+-N) in percolation water collected from soil depths of 20-40, 40-60, 60-80 and 80-120 cm. But nitrate nitrogen (-N) and total N (TN-N) had relatively higher averaged concentrations during seedling stage and showed gradually decreased trend with soil depths; 2) the amount of TN-N percolated in 80-120 cm soil depth accounted for 1.69%-2.04% of N application rate which could presented the amount of N percolated into groundwater. Relatively higher amount of NH4+-N percolation happened during tillering stage. However, higher amounts of -N and TN-N happened during seedling stage. The amounts of NH4+-N and -N showed parallel level in TN-N percolated from soil; 3) increased N application rate decreased fertilizer N use efficiency and accelerated risk of N percolation in soil.