By means of both field investigation samples and indoor analysis, The inorganic nitrogen fractions and profile distribution characteristic in vegetable soil derived from river alluvial in dongting lake plain were researched. The result indicated that the content of total nitrogen varies from 0.65~1.67 g/kg, the average value and coefficient of variation is respectively 1.25 g/kg and 15.54%. The average value of fixed ammonium is 290 mg/kg, accounting for 23.2% of total nitrogen. The content of NO3－-N and NH4+-N is respectively 46.00 mg/kg and 1.91 mg/kg. The content of total N, NH4+-N, and fixed ammonium decreased with the increasing of soil profile depth in 0~80 cm. NO3－-N display leaching phenomenon from surface soil to subsoil.