【 Objective 】 In winter oil seed rape production, there is a widespread practice of overapplying nitrogen fertilizer in pursuit of high yields, which leads to low economic returns and significant nitrogen losses, thereby increasing environmental risks. Determining the appropriate nitrogen fertilizer application rate is crucial for achieving high yields and environmental sustainability in winter oil seed rape. 【 Method 】 Field experiments were conducted in three major winter rapeseed production areas in the middle and lower reaches of the Yangtze River Jingmen in Hubei Province, Chizhou in Anhui Province, and Zhenjiang in Jian gsu Province from 2019 to 2020. Five nitrogen fertilizer application rates (0, 90, 180, 270, and 360 kg·hm 2 ) were set to investigate the effects of nitrogen fertilizer rates on winter oil seed rape yield, nitrogen accumulation, residual inorganic nitrogen in soil, and apparent nitrogen balance. The relationship between yield and nitrogen input output balance was comprehensively evaluated to determine the appropriate nitrogen fertilizer application rate for winter rapeseed that is both high yielding and envi ronmentally friendly 【 Result 】 The results showed that nitrogen application significantly increased oil seed rape yield, with a trend of increasing yield as the nitrogen application rate increased. When the nitrogen application rate reached 270 kg·hm 2 , the y ield tended to stabilize, with an average yield of 3 146 kg·hm 2 for the two varieties at each of the three experimental sites. The trend of nitrogen accumulation in the aboveground parts was consistent with that of yield. When high or excessive nitrogen w as applied, the nitrogen accumulation in non seed organs significantly increased. Compared with 270 kg·hm 2 , when the nitrogen application rate increased to 360 kg·hm 2 , the average nitrogen accumulation in plants increased by 6.85%, and the proportion of nitrogen in non seed organs increased by an average of 0.49 percentage points. The residual inorganic nitrogen in the soil at the oil seed rape harvest stage and the nitrogen balance of the soil plant system were positively correlated with the nitrogen appl ication rate, showing a trend of slow growth followed by a sharp increase as the nitrogen application rate increased. When the nitrogen application rate was 270 kg·hm 2 , the average residual inorganic nitrogen and apparent nitrogen surplus were 40 kg·hm 2 and 95 kg·hm 2 , 【 Conclusion 】 Based on the allowable apparent nitrogen surplus for maintaining crop yield and soil fertility (80 kg·hm 2 ), the recommended nitrogen fertilizer application rates for the three experimental sites in Hubei, Anhui, a nd Jiangsu were 207, 219, and 250 kg·hm 2 , respectively, with corresponding average yields of 3 083, 3 054, and 3 149 kg·hm 2 , and residual inorganic nitrogen in the topsoil of 22, 45, and 51 kg·hm 2 , respectively. These recommended rates can ensure stable winter oil seed rape yields while controlling the risk of nitrogen loss, contributing to achieving the dual goals of high yield and environmental friendliness in winter oil seed rape production.