This study explored the effects of a 20% reduction of chemical fertilizer nitrogen combined with the application of biochar and rapeseed cake on increasing the yield and the synergistic effect in the production of maize-cabbage rotation in the yellow soil area of Guizhou by pot experiment.Five treatments were set up，including no fertilization(CK)，conventional chemical fertilizer(CF)，20% reduction of chemical fertilizer nitrogen combined with biochar(RF+B)，20% reduction of chemical fertilizer nitrogen combined with rapeseed cake(RF+O)and 20% reduction of chemical fertilizer nitrogen combined with biochar and rapeseed cake(RF+BO)，and their effects on dry matter mass，nutrient uptake，nitrogen use efficiency，and yields of corn and cabbage were studied. The results showed that the overall effect of RF+BO was the best among the three combined application treatments. The RF+BO treatment could meet the nutrient requirements of maize and cabbage during the growth period and effectively improved the uptake of nitrogen，phosphorus，and potassium. Compared with the CF treatment，the absorption of nitrogen，phosphorus and potassium in maize and cabbage increased by 27.59%，37.21%，30.34% and 26.64%，35.56%，33.44%，respectively. RF+BO treatment is beneficial to improving the nitrogen use efficiency of maize and cabbage in the current season. Compared with the CF treatment，the contribution rate of nitrogen fertilizer，agronomic efficiency，partial productivity and apparent nitrogen use efficiency in the maize season increased by 1.64%，9.88%，8.36%，26.21%，and increased by 2.99%，35.70%，33.71% and 31.78% in the cabbage season，respectively. The yield increase effect was remarkable，and the yields of maize and cabbage increased by 9.72% and 39.26%，respectively，compared with CF treatment. In conclusion，applying biochar and rapeseed cake with a 20% reduction in chemical fertilizer nitrogen can provide a theoretical basis for reducing chemical fertilizer and increasing the efficiency of fertilization technology for maize-cabbage in the yellow soil area of Guizhou.