This study aimed to solve the problem of excessive dependence of rice yield on pure chemical nitrogen fertilizer, the environmental problem and high efficiency utilization of chemical nitrogen fertilizer, and even the scientific application of biochar in paddy field. A field experiment was conducted from 2019 to 2021 in Sinan county, Guizhou province. Taking no fertilization as the control (CK), five treatments of chemical nitrogen fertilizer dosages: T0~T4, i.e., 100%, 90%, 80%, 70% and 60% of nitrogen fertilizer, respectively, was set up under the principle of equal total nitrogen application. The rice yield, yield components and nitrogen, phosphorus and potassium uptake and utilization were studied. The results showed that biochar application with reduced nitrogen fertilizer significantly affected the yield, yield composition, aboveground nitrogen, phosphorus and potassium accumulation, and nitrogen, phosphorus, and potassium utilization efficiency of rice. The grain yield and nitrogen, phosphorus and potassium accumulation of rice increased first and then decreased with the increase of biochar application amount and the decrease of nitrogen fertilizer. The highest actual and theoretical rice yield were found under T2, T3 and T2 respectively in 2019, 2020 and 2021, which three significantly increased by 16.04%, 17.94% and 14.73%, and 55.72%, 64.08% and 118.91%, respectively, compared with T0. The accumulation of N, P₂O₅ and K₂O, partial productivity, agronomic efficiency, apparent utilization, and harvest index of rice grains were also higher. So T2 and T3 were the relatively better treatments with reduced nitrogen fertilizer application of biochar. The regression equation of yield-biochar application and extreme value analysis showed that the applied nitrogen fertilizer decreased by 21.76%, 24.60% and 19.00%, respectively in 2019, 2020 and 2021, i.e., 32.64, 36.90 and 28.50 kg/hm².The highest rice yield (7.80, 8.57 and 8.03 t/hm², respectively) was obtained at the biochar application of 5.44, 6.15 and 4.75 t/hm², these yields were increased by 22.52%, 18.78% and 13.74%, respectively, compared with T0. Application of biochar with reduced N fertilizer significantly increased the utilization rate of N, P and K of chemical N, P and K fertilizers, but decreased the utilization rate of that of the chemical fertilizers plus biochar. Therefore, N, P and K fertilizers should be reduced simultaneously when applying biochar in Guizhou yellow soil paddy fields, the reduction percentage of which are 19.00%~24.60% and best application rate of biochar is 5.00~6.25 t/hm². This study has important guiding significance for N, P, and K fertilizer reduction and biochar application in yellow soil paddy fields in Guizhou Province.