To effectively reduce nitrogen lossin slope farmland in purple hilly area,a randomized block experiment with two factors and four levels was designed and simulated runoff plot method was taken in this experiment.The objective of this study was to identify the influence of nitrogen form on the dynamics of soil nitrogen loss of sloping farmland in rainy season.The results showed that the nitrogen loss in the rainy season account for 3.29% of the nitrogen fertilizer amount,and the nitrogen loss in maize growing season and after maize harvest account for 1.63% and 1.65% of the nitrogen fertilizer amount,respectively.The nitrogen loss was determined by both nitrogen fertilizer form and the interval between fertilizing and runoff.There was no significant difference about the nitrogen loss among different nitrogen fertilizer forms before May 22.The nitrogen loss between Jul 30 and Aug 4 in ammonium nitrogen and amide nitrogen fertilizer treatment was 3.65 kg/hm2 and 4.35kg/hm2,respectively,which were higher than the other two treatments.The nitrogen loss in Sep 16 in nitrate fertilizer and slow controlled release fertilizer treatments was 2.95 kg/hm2 and 3.17 kg/hm2,which were 119.95% and 103.96% higher than the values in ammonium nitrogen fertilizer treatment.The total nitrogen loss was decreased when nitrate and slow controlled release fertilizer was applied.The nitrogen loss was sharply increased in the latter seasons when ammonium nitrogen and amide nitrogen fertilizer was applied.Thus in order to decrease the nitrate loss,the nitrate and slow controlled release fertilizer was recommended for corn fertilization.