Abstract: Based on the N balance parameters and statistical data,the characteristics of N loss and its environmental effects for the dominant crops of winter wheat and summer maize in Huang-Huai-Hai plain were studied.The results indicated that with the increase of N fertilizer application from 1992 to 1998,the total N loss, ammonia volatilization loss, nitrificattion-denitrification loss, leaching and runoff per unit area were gradually increased. The residual rate,loss rate and utilization efficiency were different for N fertilizers and crops;the loss of N fertilizers was much higher in the field of summer maize than that in the field of winter wheat. At last, the environmental effect of N loss and possible countermeasures were discussed.