Abstract: Soil microbes at the rhizosphere are key factors in maintaining soil health and vigor, yet there are effects of coupled soil moisture and biochar on the microbial environment of the soil at the rhizosphere. However, the effect of different water-biochar coupling on rhizosphere soil microorganisms is not clear. Asparagus is a perennial rooted herbaceous plant, with the growth of the extension of the years leading to the asparagus continuous cropping disorder is more and more serious, the growth of weak, lower yield, poor quality and other problems are becoming increasingly prominent. The deterioration of soil physicochemical properties and the imbalance of rhizosphere soil microbial community are the root causes of asparagus crop failure. To explore the effects of water-biochar coupling on the structure of soil microbial communities in the asparagus rhizosphere and the mechanisms that regulate the asparagus rhizosphere ecosystem. In this study, through the field positioning experiment of asparagus planting, we set up four irrigation levels (W₀: severe deficit irrigation, I = 320 mm; W₁: middle deficit irrigation, I = 375 mm; W₂: mild deficit irrigation, I = 430 mm; W₃: adequate irrigation, I = 480 mm, I represents the amount of irrigation) and four biochar application levels (0 t/hm² (B₀), 10 t/hm² (B₁₀), 20 t/hm² (B₂₀), and 30 t/hm² (B₃₀)) were used in a field localization experiment, and Illumina next-generation sequencing (NGS) technology was used to study the changes in the structure and abundance of the soil microbial community in the asparagus rhizosphere by the different water-biochar coupling treatments. The results showed that moderate deficit irrigation promoted the formation of asparagus rhizosphere soil bacterial abundance and diversity, and the relative abundance of asparagus rhizosphere soil fungi increased by 4.48% to 22.05% with increasing soil moisture; biochar application increased the abundance and diversity of rhizosphere soil microorganisms compared to no biochar application. Compared with the B₀ and B₁₀ treatments, the number of rhizosphere bacterial communities increased by 1.76% and 0.51%, and the number of fungal communities decreased by 1.38% and 0.13% under the B₂₀ (20 t/hm²) treatment, respectively, whereas there was a significant inhibitory effect of the application of 30 t/hm² biochar on both. In addition, there was no significant effect on the structure of bacterial and fungal communities under different water-biochar coupling conditions, but compared with the no biochar application treatment, the biochar application reduced the growth and reproduction of the root rot causal fungus Fusarium, and improved the asparagus rhizosphere soil microenvironment. Optimal deficit irrigation helps to maintain microbial diversity and community stability. Soil bacterial community numbers were higher in the medium and mild deficit irrigation treatments than in the other irrigation levels, and community richness and diversity of rhizosphere soil bacteria were greatest at the medium deficit irrigation level. The W₁B₂₀ treatment not only promoted the growth of bacterial community, but also suppressed the abundance of harmful fungal community, which was more favorable to regulate the asparagus rhizosphere ecosystem. This study provides theoretical basis for the regulation of the perennial asparagus rhizosphere soil microcosm in continuous cropping and the sustainable development of agriculture in the seasonal arid areas of Southwest China.