Abstract: Biodegradable film has been proven to be a good substitute for traditional refractory plastic film in the cultivation of maize, cotton and sunflower due to the similar effects of improving soil temperature and moisture, and increasing yield. However, whether biodegradable film mulching can reduce the accumulation of soil nitrate, soil organic matter content and affect the nutrient uptake by plants or not is not clear. Therefore, 3 treatments including traditional refractory plastic film(PM), biodegradable film(JM) and no film(CK) were set up in the present study to systematically analyze and compare their effects on above-ground dry matter, soil organic matter, soil nitrate accumulation, nutrient uptake and seed yield of winter oilseed rape(Brassica napus L.) in 2 growing seasons(2012-2013 and 2013-2014). The results showed that the above-ground dry matter in PM and JM at all growth stages were higher than that in CK, and no obvious difference was found between PM and JM. Soil organic matter in CK at 0-60 cm soil depth were higher than that in PM and JM at 60, 150 and 240 days after sowing(DAS), and significant difference was not found between PM and JM at 60 and 150 DAS; but at 240 DAS, soil organic matter in JM was significantly higher than in PM. Soil nitrate nitrogen accumulation at 0-200 cm soil depth fell fast in 0-60 and 150-240 DAS, and decreased slowly in 60-150 DAS. The variation trend of soil nitrate accumulation with soil depth at 60 and 150 DAS among PM, JM and CK were consistent in the same year, but significantly difference was found at 240 DAS. In 2012-2013, a drought season, an obvious peak(15.2 kg/hm²) at 80 cm soil depth was discovered just in PM, but JM and CK had no obvious peak. In 2013-2014, a wet season, PM had 2 obvious peaks at 80 and 160 cm soil depths, with the values of 14.7 and 17.3 kg/hm², respectively, but JM and CK only had 1 obvious peak, with the values of 14.3 and 11.5 kg/hm², respectively. Seed yield and nitrogen, phosphorus and potassium uptake of winter oilseed rape at seedling, flowering and harvesting stages were almost the same between PM and JM, which were all significantly higher than CK. Compared to PM, the seed yield in JM had no significant difference and the seed nitrogen, phosphorus and potassium uptake at harvesting was similar, but the soil organic matter increased by 7.0% and nitrate accumulation reduced by 34.1% at 240 DAS. Traditional plastic film consumed soil fertility excessively at the late growth stage, which wass unfavorable for the sustainable development of agriculture, and the nitrate nitrogen residue in the soil was higher than biodegradable film, which had more serious risk potential for groundwater pollution. Biodegradable film was recommended for winter oilseed rape cultivation.