The effects of three kinds of microbial inoculants and its compound inoculants on the soil fertility， tree nutrition， fruit quality and yield of satsuma mandarin were compared and analyzed with field trials to guide the rational application of microbial inoculants in citrus and to improve the yield and quality of citrus fruit.The results showed that the application of microbial inoculants increased soluble solids， solid acid ratio and vitamin C of satsuma mandarin fruit compared with no application of microbial agents.Compound microbial inoculants improved the fruit quality and stabilized the yield of fruit compared with single bacterial treatment.Different microbial inoculants increased the contents of soil organic matter， available nitrogen， phosphorus and potassium， the activities of urease， phosphatase and sucrase.Through linear mixed model analysis， the total phosphorus， soil phosphatase and available phosphorus in leaf were the important indexes significantly affected the quality of satsuma mandarin fruit.It is indicated that different microbial inoculants can improve the activation of soil phosphorus， increase the soil available phosphorus， promote the phosphorus uptake by the tree， and finally improve the fruit quality， among which the compound microbial inoculants have more significant effects.