Abstract: By collecting surface soil of different crop types in the peripheral zone of Danjiangkou hydrofluctuation belt, the total nitrogen content of 0-10 cm (A) and 10-20 cm (B) soil layer were measured, and the distribution characteristics of soil nitrogen content in Danjiangkou hydro-fluctuation belt were analyzed. The content of nitrogen was determined by spectrophotometry. The results showed that in the hydro-fluctuation belt, with the increase of soil depth, the total nitrogen content of different crop types decreased, which indicated that the total nitrogen content decreased with the increase of soil depth. In different crop types, the soil nitrogen content was different, the total nitrogen content in A layer of pumpkin field was the highest, then was eggplant field and soybean field, the lowest was cotton field; in layer B, similarly, the total nitrogen content in pumpkin filed was the highest, then was mung field and corn field, the lowest was sorghum field. The total nitrogen content of A layer was the highest in Yun County, then was Danjiangkou City, and the lowest was Xichuan County; total nitrogen content of B layer was the highest in Danjiangkou City, then was Xichuan County, the lowest was Yun County.