Abstract: The effect of irrigation on soil nitrate leaching and uptake was conducted with sandy loam soil in the valley of Wudian River. The main results showed as follows: there is a linear relationship between the amount of irrigation water and corn yield, and between the amount of irrgation water and uptake N by corn crop within the range of 0～4000m 3/hm 2 irrigation water. The NO3--N mainly concentrated in 0～60cm soil layer, the peak of which was at 40cm. The remained NO3--N in 0～80cm soil layer was decreased with the increase of irrigation water, and there is no relationship between the remain NO3--N and amount of irrigation water in 80～320cm soil layer, but the remain NO3--N was increased with the increase of irrgation water in 320～400cm soil layer. The relationship between the remained NO3--N and amount of irrigation water was hyperbola at the different depth of soil profile. The N lost from treatment without irrigation and with 4000m 3/hm2 irrigation was lowest. The leaching loss of NO3--N could be decreased with the increase of large amount of irrigation water in right way, the main reasons of which were analysed and gave out the concept of NO3--N leaching and uptake effect.