Soil microbial communities, key players of many crucial ecosystem functions, are prone to degradation due to intensified environmental perturbations. However, few ecological concepts and practices have been developed for rescuing these degraded microbial communities. Here, we carried out a pot experiment (totally 324 pots) with or without arbuscular mycorrhizal fungi (AMF) inoculation and at three levels (one, three and six species) of plant diversity to disentangle how the AMF and vegetation rescue the soil nitrogen (N) -cycling microbial loop. Our results provide strong evidence that AMF inoculation improved the restoration of soil N-cycling microbial communities. This improved restoration is related to the role of AMF in enhancing interactions within the N-cycling microbial loop. Furthermore, increased plant diversity strengthened the role of AMF in rescuing degraded N-cycling microbial communities. Our findings provide novel insights into the roles of AMF and plant diversity in facilitating the rescue of microbial communities in degraded terrestrial ecosystems.