The plastic film mulching and nitrogen fertilizer application are important agricultural patterns in arid area, which lead to serious residual plastic film in soil and low nitrogen use efficiency. The biodegradable film mulching and optimal nitrogen application can solve these problems. Different film mulching and different nitrogen application levels treatments were set, and experiment was carried out in both years in the farm of Wulanbuhe, Hetao Irrigation District. Four kinds of nitrogen levels under biodegradable film mulching was applied, including no nitrogen (BM0 for 0kg/hm2), low nitrogen (BM1 for 160kg/hm2), medium nitrogen (BM2 for 220kg/hm2) and high nitrogen (BM3 for 280kg/hm2). The base fertilizer nitrogen rate of low nitrogen, medium nitrogen and high nitrogen all were 56kg/hm2, and high nitrogen with plastic film mulching (PM3) and high nitrogen with no mulching (NM3) treatment as controls were used, so there was six treatments in all. The effects of different film mulching and different nitrogen application rates on the distribution, accumulation, leaking and utilization efficiency of nitrogen in soil were studied. The results showed that the average nitrate content for biodegradable film mulching in the 0~50cm soil layer was decreased by 9.49% and 28.84%, respectively, in the third and fourth degradation stages compared with plastic film mulching, but it was increased by 20.46% and 25.74% for biodegradable film mulching compared with no film mulching （P<0.05). The corn nitrogen content for biodegradable film mulching was only 2.26% lower than that of plastic film mulching and 3.36% lower for nitrogen leaching during the whole corn growth stage. However, the corn nitrogen content was increased by 8.90% and 11.38% for biodegradable and plastic film mulching than that of no film mulching, respectively, and 22.01% and 26.25% increased for nitrogen leaching. There was no significant difference in yield between biodegradable film mulching and plastic film mulching, which was 13.67% and 18.38% higher than that of no film mulching, respectively （P<0.05). The soil nitrate content, corn nitrogen content, nitrogen leaching and yield were all increased with the increase of nitrogen application amounts, and the nitrate content in 0~30cm soil layer was increased by 49.45% and 135.78% for BM3 compared with those of BM2 and BM1, and increased by 0.78% and 24.54% for nitrogen content in corn, 84.08% and 255.37% increase for nitrogen leaching （P<0.05), and 0.16% and 35.37% increase for corn yield （P<0.05). The BM2 treatment (topdressing with 220kg/hm2) had the highest combined efficiency of nitrogen, and the application of 1kg nitrogen fertilizer can produce 27.99kg corn, which was the best fertilization pattern in this area under biodegradable film mulching.