As animal husbandry advances, the demand for premium feed has seen substantial growth, while the availability of natural forage resources remains limited. Corn stover, characterized by its high yield and rich nutritional content, has become a vital source of roughage. The application of silage technology to corn stover enhances its palatability, improves its nutritional value, and exerts positive effects on livestock production performance. This study aims to evaluate the impact of different additives and their proportions on the nutrient composition, fermentation quality, and microbial community structure of corn stover silage. Specifically, Lactobacillus plantarum, cellulase preparations (commercial cellulase enzyme preparations), and xylanase preparations (commercial xylanase enzyme preparations) were employed as additives to investigate their synergistic effects and underlying mechanisms during the silage process. Furthermore, dosage gradients were established to determine the optimal dosage range, providing a robust scientific basis for the optimization of additive applications. In this experiment, corn stover was used as the substrate, with the moisture content maintained at 60%. Treatments with Lactobacillus plantarum, cellulase, and xylanase were applied, and silage samples were analyzed after 30 and 60 days of fermentation to assess fermentation quality, nutritional quality, and microbial community structure. The findings revealed that the nutritional quality of corn stover silage improved progressively with fermentation time. Compared to the control group, the addition of Lactobacillus plantarum, cellulase, and xylanase significantly increased the abundance of lactic acid bacteria, reduced the pH value, and effectively suppressed the proliferation of spoilage microorganisms. Among the treatments, xylanase demonstrated the most pronounced effects, substantially increasing lactic acid and soluble carbohydrate content while reducing levels of neutral detergent fiber (NDF) and acid detergent fiber (ADF). Notably, the incorporation of 20 U/g xylanase into the silage process facilitated the breakdown of xylan in corn stover into soluble carbohydrates, thereby providing essential substrates for lactic acid bacteria and other beneficial microorganisms. This, in turn, inhibited the growth of harmful microorganisms, ultimately improving the nutritional quality, fermentation quality, and microbial community structure of the silage. These findings provide a theoretical framework and practical guidance for optimizing the production of corn stover silage, promoting efficient resource utilization, and supporting the sustainable development of animal husbandry.