To study the mechanism of straw incorporation at different depth with inoculants on the effectiveness of activating phosphorus by soil microorganisms，the paddy soil from yellow brown soil was collected and incubated in this experiment.Four straw incorporation depths were conducted:0，10，20 and 30 cm(S0，S10，S20 and S30)，and straw returning+inoculant treatments were set up in different depths(S0+F，S10+F，S20+F，S30+F)to compare the effects of straw at different incorporation depths on microbial carbon(MBC)，microbial phosphorus(MBP)，phosphatase activities，bioactive phosphorus fractions and phoD gene functional microorganisms.Results showed that，comparing with S20 and S30 treatments，the MBC，MBP，acid phosphatase activity and bioactive phosphorus fractions content under S10 treatment were significantly higher.Compared with S10 treatment，the contents of mineral occluded，chelate-extractable phosphorus and enzyme extractable organic phosphorus were increased by 8.5%-20.3% under the S10+F treatment.The copy number of the phoD gene under S10 treatment increased by 276.2% compared to S30 treatment.At the phylum level of phoD genecontaining microbial community composition，S10 treatment mainly increased the relative abundance of Actinobacteria.At the genus level，S10 treatment primarily increased the relative abundance of Pseudomonas and Sinorhizobium.Incorporating straw at a depth of 10 cm could enhance soil phosphatase activity by increasing the abundance of phoD gene-containing microbes，which in turn boosted the content of biologically available phosphorus fractions in the soil.This depth should be considered optimal for straw incorporation to enhance soil phosphorus effectiveness，particularly when combined with an inoculant.