Abstract: For improving the use efficiency of nitrogen fertilizer and decreasing the losses of nitrogen fertilizer, the rules of nitrogen transformation and distribution under film hole irrigation with urea solution were studied through laboratory simulation experiment. The results showed that the ammonium nitrogen mainly distributed around film hole and decreased with the increasing of distance from film hole. The ammonium nitrogen content increased gradually in the early 0-5 d and decreased subsequently after the fifth day. The nitrification was weak before the seventh day and the nitrate nitrogen content in the top soil layer was lower than background value. The nitrification was enhanced after the seventh day. The nitrate nitrogen content in the top soil layer was more than background value; the nitrate nitrogen content in the horizontal direction was more than in the vertical direction after the seventh day. During the course of urea transformation, the decrement of ammonium nitrogen was far more than the increment of nitrate nitrogen. The research results provide reference for further study of film hole irrigation and fertilizer application.