【Objective】 Summer fallow after winter wheat harvest in dryland is a common practice on the Loess Plateau. However, due to bare land and intensive rainfall during summer fallow, the leaching characteristics of residual fertilizer nitrogen (N) after crop harvest deserve attention. This study aimed to reveal that the destination of applied N fertilizer after wheat season and the leaching characteristics of residual N fertilizer during summer fallow in dryland of the Loess Plateau. 【Method】 This study was carried out in large lysimeters (3 m×2.2 m×3 m) by the ¹⁵N labeled method. ¹⁵N labeled urea was applied at the beginning as basal fertilizer with the rate of 150 kg·hm^-2.Firstly, the absorption of ¹⁵N labeled fertilizer by wheat and the residual N in the soil after wheat harvest were investigated, and subsequently the ¹⁵N abundance and content changes of residual ¹⁵N labeled fertilizer in the soil profile were measured during the summer fallow of three years (2015—2017). 【Result】 The results showed that the average absorption of nitrogen fertilizer by wheat was 53.9% while the amount of ¹⁵N fertilizer distributed in the soil (0-100 cm) after wheat harvest was 36.3% of the N application rate, with an average of 40.1% being in nitrate form. In the first year, the residual ¹⁵N fertilizer which accumulated in the 0-40 cm soil layer moved downward and accumulated in the 60-80 cm soil layer during the following summer fallow. The ¹⁵NO₃^--N mainly accumulated in the above 80 cm soil layer before summer fallow, but the accumulation peak of ¹⁵NO₃^--N was in the 80-100 cm soil layer at the end of fallow. In the second and third years, the residual ¹⁵N fertilizer and ¹⁵NO₃^--N moved downward about 20 cm, respectively, during summer fallow. After the summer fallow, the amount of residual ¹⁵N fertilizer in the 0-100 cm soil layer decreased, but the amount of residual ¹⁵N fertilizer and ¹⁵NO₃^--N in the 100-200 cm soil layer both increased. Specifically, the amount of residual N in the 100-200 cm soil layer increased by 1.9 and 7.0 kg·hm^-2during the summer fallow of the second and third years, respectively. Also, the amount of ¹⁵NO₃^--N in the 100-200 cm soil layer increased by 2.7 and 7.0 kg·hm^-2during the summer fallow of the second and third years, respectively. 【Conclusion】 During the summer fallow, residual N fertilizer leached significantly. Under normal precipitation conditions, the average downward migration rate of residual N fertilizer during a summer fallow was 20 cm. As the age increased, the residual N fertilizer in the 0-100 cm soil decreased; while it increased in the 100-200 cm soil layer, with nitrate as the main leached form. However, the cumulative total loss of residual N fertilizer in the 0-200 cm soil profile during summer fallow was small, indicating that the redistribution of residual N fertilizer nitrogen in the soil profile was the main mechanism.