Under the condition of equal nitrogen，phosphorus and potassium fertilization，the experimental study on the effect of improved fertilization on soil properties in orchard alkaline soil was carried out in order to obtain the technical scheme of improved fertilization in alkaline soil and provide theoretical basis for the application of improved technology in orchard alkaline soil. The effects of different alkaline soil improvement and fertilization treatments on soil properties of Orah orchard were studied by using eight-year-old Orah varieties with Citrange as the base stock and Fukumoto navel orange as the intermediate stock. Six experimental treatments were set up，including conventional compound fertilizer(CF)，formula fertilizer(urea + potassium sulfate + calcium superphosphate，FF)，compound fertilizer + sulfur powder(CF+S)，compound fertilizer + desulfurized gypsum(CF+T)，formula fertilization + sulfur powder(FF+S)，and formula fertilizer + desulfurized gypsum(FF+T). Compared with CF treatment，the improved fertilization of different alkaline soils increased the total porosity and organic matter content of the soil，and the FF+T and CF+T treatments were relatively the largest，which increased by 9.2% and 60.1% compared with the CF treatment. At the same time，the content of soil nutrient elements was increased in different degrees，and the FF+T treatment was the highest. The soil bulk density，pH value and Na+ exchange capacity of each alkaline soil improved fertilization treatment were reduced，and the FF+T treatment was the smallest，which was 9.7%，15.6% and 16.7% lower than that of CF treatment，respectively. The activities of soil sucrase，urease，alkaline phosphatase and catalase in FF+T treatment were the highest，which were 17.8%，43.8%，48.8% and 38.4% higher than those in CF treatment，respectively. The soil carbon emission flux of the orchard was relatively large in July and relatively small in December，and the FF+T treatment was the smallest，which was 25.5% and 12.7% lower than the CF treatment，respectively. The order of the comprehensive scores of the principal components of each treatment was FF+T>CF+T>FF+S>CF+S>FF>CF，that was，the effect of FF+T treatment on improving the soil properties of the citrus orchard was relatively optimal.