【Objective】This study aimed to investigate the effects of different mulching treatments on microbial diversity and community structure of maize inter-root soil under the planting mode of “dryland triple intercropping”. 【Method】We conducted a two-year randomized block group field experiment with four treatments: no mulching (control), straw mulching (S), milk vetch mulching (M), and combined mulching of straw and milk vetch (S+M). Sequencing of internal transcribed spacer region (ITS ) rDNA and 16S rRNA genes using Illumina MiSeq PE300 high-throughput technology was used to analyze changes in microbial characteristics of maize soils at the flowering stage after mulching. 【Result】The main results were as follows: (1) The M and S+M treatments decreased the number of soil bacterial species and community diversity, the S and S+M treatments increased the number of soil fungal species and community diversity, while the M treatment decreased the number of soil fungal species. The differences in soil bacterial composition and community structure between the mulched treatments (S, M, S+M) and the no-mulch treatment were significantt; fungal communities were not interspersed with each other, differed significantly, and did not have similar community composition between treatments. (2) Mulching treatments decreased endemic bacterial species whereas S and S+M treatments increased fungal species endemic to each treatment.Compared with the control treatment, the mulching treatment increased the relative abundance of Proteobacteria, Actinobacteria, and Basidiomycota in the dominant bacterial phyla of the rhizosphere soil of maize, and decreased the relative abundance of Acidobacteria and Ascomycota. (3) The S+M treatment affected the bacterial microbial community structure by influencing total phosphorus and nitrate nitrogen, which were positively correlated with dissolved organic carbon and readily oxidizable carbon, while the M and S+M treatments affected the fungal microbial community structure by influencing total nitrogen and nitrate nitrogen, which were positively correlated with soil water content, effective phosphorus, total nitrogen and nitrate nitrogen.【Conclusion】Compared to the control treatment, the mulching treatments were able to improve soil microbial diversity and community structure, accelerate the decomposition of straw and milk vetch in the field to promote the absorption and utilization of soil nutrients by maize, and positively contribute to the soil ecological balance. Of all the treatments, the synergistic mulching treatment of straw and milk vetch was the most effective. Therefore, synergistic mulching treatment with straw and milk vetch is an effective measure for conservation tillage in the drylands of Southwest China.