Abstract: Based on a field plot experiment, the effects of straw-decomposition inoculants addition with straw returning on soil nutrient change characteristics and microbial diversity of phosphorus solubilizing bacteria in of a rice-wheat rotation system were studied, through the investigations of soil aggregates water stability, physicochemical properties, enzyme activities, phoD microbial community structure and diversity. Two treatments were set up in this experiment: conventional fertilization + straw returning (CK) and conventional fertilization + straw returning + straw-decomposition inoculants (IT). The composition of the straw-decomposition inoculants was mainly Bacillus subtills and Trichoderma harzianum, and the number of effective viable microorganism was higher than 200 million · g^-1. The results show that, under IT, the straw decomposition rate was significantly higher than that of CK by 42.1%. The water stability of soil aggregates was significantly increased, and the mean weight diameter (MWD) of soil was significantly increased by 46.7%. The number of large aggregates R_0.25 and geometric mean diameter (GMD) were increased by 62.5% and 22.2%, respectively, but there was no significant difference between CK and IT. The contents of organic matter, available nitrogen, available phosphorus and the activity of soil alkaline phosphorus were raised under IT by 11.8%, 59.8%, 62.6% and 33.8%, respectively, but there was no significant difference in pH, EC, humic acid, total nitrogen, total phosphorus, total potassium and available potassium between the two treatments. The yield of wheat was not significantly increased under IT, but the total phosphorus content of grain under IT was significantly higher than that of CK by 28.1%. Based on the comparative analysis of phoD microbial community, IT significantly increased the number of phoD community species and altered the phoD community structure significantly, but there were no significant differences in the phoD community diversity indexes between the two treatments. The results of redundancy analysis (RDA) demonstrate that phoD community structure was significantly correlated with soil pH, available nitrogen (AN) and MWD. In conclusion, the addition of straw-decomposition inoculants is conducive to improve the soil structure, increase soil available phosphorus content and optimize the soil phoD microbial community structure, so that, effectively improve the soil phosphorus supply efficiency in the rice-wheat rotation system.