Under natural rainfall conditions, a field plot experiment (2014-2015) was conducted to study the effects of different fertilization modes (i.e. conventional fertiliser application, T1; reduced fertiliser application, T2; optimized fertiliser application, reduced fertiliser application and wheat straw biochar application, T3) on nitrogen (N) loss by surface runoff, the apparent N balance, and vegetable yield in the vegetable field of cabbage (Brassica Oleracea L.) in Taihu Lake Basin, China. The results showed that total volume of surface runoff reached up to 1 729.20 m³/hm² during the vegetable growing season, which showed a significant positive linear correlation with rainfall capacity. In T1 treatment, total nitrogen (TN) loss by surface runoff reached up to 47.66 kg/hm² during the vegetable growing season. Compared with T1, T2 and T3 significantly reduced TN losses by 13.95% and 23.68%, respectively. Compared with T2, TN loss decreased significantly by 11.31%, after application of wheat straw biochar (T3). The lost N was mainly nitrate nitrogen (NO₃^--N), which accounted for 81.11%~85.94% of TN loss. Meanwhile, N surplus amount in the vegetable field of cabbage reached up to 158.24 kg/hm² under T1 treatment. With decreasing N application in the vegetable field, N surplus significantly decreased. Compared with T1, N surplus decreased significantly by 29.03%~39.81%. Furthermore, T2, T3 significantly reduced cabbage head yield by 16.12%~19.11%, but the sphericity index increased significantly by 6.17%~7.41%, and the partial factor productivity of nitrogen (PFPN) for cabbage head increased significantly by 24.39%~28.98%. And, compared with T2 treatment, after application of wheat straw biochar (T3) in the vegetable field, cabbage head yield and PFPN increased slightly, but no significant difference was found.