Abstract: This study aimed to assess the impacts of the inoculation of arbuscular mycorrhizal fungi (AMF) and rhizobium on soil nitrogen (N) and phosphate (P) availability in monoculture and soybean/maize incorporating systems. We designed a greenhouse experiment as follows: Three planting patterns, including soybean/maize intercropping, maize monoculture, and soybean monoculture; Four microbial treatments, including inoculating with AMF, inoculating with rhizobium, dual inoculation (both AMF and rhizobium), and non-inoculation as a control. The results showed that intercropping of soybean/maize significantly promoted maize and soybean growth, and increased concentrations of soil available N and P concentrations compared to monoculture. Dual inoculation of AMF and rhizobium further promoted plant growth and enhanced soil available N concentration compared with that non-inoculated or only inoculated with AMF or rhizobium in the soybean/maize intercropping system. The redundancy analysis showed that dual inoculated with AMF and rhizobium in soybean/maize intercropping was most conducive to the concentrations of ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3−-N), and available phosphorus (AP) in the soil. The overall correlation analysis indicated that AP was positively related to AMF symbiosis, while NH4+-N and NO3−N were positively correlated with plant biomass. Inoculating with both AMF and rhizobium in the soybean/maize intercropping system improved the soil available N and P, improving the advantages of legume/graminaceous intercropping.