The vermicompost coupled with coal-based soil conditioner has the potential to improve soil physicochemical properties and enhance the growth of plants. It plays a crucial role in facilitating the biogeochemical cycling of elements and maintaining ecological balance in ecosystems. However, there is still insufficient evidence on the specific promotion mechanisms. To investigate the effects of coal-based soil conditioners and vermicompost application on sandy soil ecosystem multifunctionality and growth characteristics of Leymus chinensis (Trin.) Tzvel. (L. chinensis), a field trial was conducted in semi-arid region. Treatments include T1 (vermicompost: soil conditioner = 1:2), T2 (1:1), T3 (2:1), and control check (CK). Study results indicated that soil properties significantly improved when vermicompost and soil conditioner were applied at a 2:1 ratio. This treatment resulted in a substantial increase in soil moisture content, nutrients content and alkaline phosphatase (ALP) enzyme activity. Soil ALP in amendment treatments significantly increased by 61.54 % compared with CK treatment. Furthermore, the growth of L. chinensis was improved and biomass increased form 7.3-40.6 % than CK treatment. The alpha-diversity and abundance of soil microorganisms in amendment treatments were superior rather than CK treatment (p < 0.05). Moreover, soil microbial communities were primarily influenced by soil AvN, pH and AvK. The Chloroflexi was identified as the key factor when we compared between T3 and other treatments. Mantel test further showed that AvN was significantly correlated with microbial communities. Path models showed that the addition of vermicompost and coal-based conditioner enhanced the feedback effect of soil microorganisms on plant growth status in the soil-plant system. Our findings strongly demonstrated that the application of vermicompost and soil conditioner significantly improved sandy soil multifunctionality by increasing soil moisture content, enhancing nutrient contents, regulating microbial communities and facilitating plant biomass. Thus vermicompost combined with coal-based soil conditioner can be considered as a potential material to improve soil ecological functions and promote plant production.