The plot experiment was used to study the effects of biochar and organic fertilizer application on soil nitrogen loss from surface runoff and soil physical and chemical properties in Chinese cabbage field.Four treatments were set up:conventional application of chemical fertilizer (CK)，biochar combined with chemical fertilizer (B)，organic fertilizer combined with chemical fertilizer (F)，biochar + organic fertilizer combined with chemical fertilizer (BF).Soil organic matter，cation exchange capacity，aggregates，and nitrogen losses by runoff were determined.The results showed that B and F treatment significantly improved the soil organic matter and cation exchange capacity values and improved the stability of soil aggregates，compared with CK treatment.B treatment was better than F treatment in improving the content of organic matter and cation exchange capacity，F treatment was better than B treatment in improving the stability of soil aggregates，and BF treatment had the ability to improve the content of organic matter，cation exchange capacity and aggregates stability between B and F treatment.In the whole growth period，treatment B and F reduced nitrogen losses by runoff.Treatment F was better than treatment B in reducing nitrogen losses by runoff，and treatment BF was better than treatment B and F in reducing nitrogen losses by runoff.The correlation analysis showed that the total nitrogen in runoff solution was extremely significantly correlated with aggregates with particle size >2 mm (P<0.01).The loss of nitrate nitrogen by runoff was extremely significantly correlated with organic matter content，cation exchange capacity，mean mass diameter and geometric mean diameter (P<0.01) ，while it was significantly correlated with aggregates with particle size >0.25 mm (P<0.05).The loss of ammonium nitrogen by runoff was significantly correlated with organic matter content and cation exchange capacity (P<0.05).Redundancy analysis showed that the improvement of aggregate structure was the main environmental factor for the reduction of nitrogen losses by runoff.After the harvest of plant，the soil total nitrogen content of each treatment was increased，and that of treatment B was significantly higher than that of treatment F.The soil total nitrogen content of treatment BF was located between treatment B and F.Considering the loss of nitrogen by runoff and the change of soil physical and chemical properties，the effect of biochar + organic fertilizer combined with chemical fertilizer is the best.