To provide a theoretical basis for reduction of chemical fertilizers，and improvement of fruit quality and production efficiency for red pomelo production，effects of partial substitution of chemical fertilizer with organic fertilizer on the yield and fruits qualities of red pomelo and orchard soil nutrients under equal nitrogen(N)，phosphorus(P)and potassium(K)nutrients supply were studied.A field experiment was conducted from 2018 to 2020 in Fengdu county，Chongqing.There was six treatments，including FP(conventional farmer practices，pure chemical fertilizer application)，75%FP+25%OF(the ratio of organic NPK substitution on the FP-based were all 25%)，50%FP+50%OF(the ratio of organic NPK substitution on the FP-based were all 50%)，OPT(optimized fertilization)，75%OPT+25%OF(the ratio of organic NPK substitution on the OPT-based were all 25%)，and 50%OPT+50%OF(the ratio of organic NPK substitution on the OPT-based were all 50%).The NPK nutrients concentration of leaf and fruit，yield，fruit quality，and orchard soil properties were analyzed. The results showed that:(1)Compared with FP，the soil pH and the contents of the organic matter，alkali-hydrolyzed N，total N，Olsen-P，available K and slowly available K concentration in organic substitution treatments were obviously increased with the increase of organic substitution ratio.(2)Leaf N，and fruit P and K concentration were increased by 1.2%-8.5%，21.3%-48.9% and 1.29%-14.8% responded to organic substitution treatments，respectively，while there no significant effect observed on the concentration changes of leaf P and K，and fruit N.(3)Compared with FP，there was no significant change in single fruit weight，while the fruit number per plant and yield were increased by range of 0.4%-32.2% and 1.2%-30.3% in organic substitution treatments，respectively，and the yield response of optimal fertilization treatments were more obvious.(4)Fruit yield was increased first and then decreased with the increase of organic substitution ratio，and the optimized substitution ratio of organic fertilizer was 26%；in terms of fertilizer operation mode，the optimized proportion of N，P and K basal application was 52%，52% and 50%，respectively.(5)For fruit qualities，the titratable acid content in organic substitution treatments was decreased significantly compared with FP，however，both soluble solid/titratable acid ratio and soluble sugar/titratable acid ratio were increased significantly，and it showed an increasing trend with the increase of organic substitution ratio.In conclusion，substituting chemical fertilizer with organic fertilizer under equal nutrients supply realized the systematic and efficient matching of nutrient requirements from aboveground to underground of red pomelo tree by optimizing the fertilizer operation mode，improving the nutrient status of leaves and fruits，and enhancing the chemical properties of orchard soil，thereby higher fruit yield were obtained via increasing the number of fruits per plant，and the fruit quality was effectively improved as well.