The experiment was designed to investigate the effects of the composite bacterial agent composed of Lactobacillus plantarum， Bacillus subtilis and Aspergillus niger and its compounding with molasses or cellulase on the silage quality and microbial diversity of corn straw. A single-factor randomized design was adopted with four treatments： control group （CK）， composite fungicide group （BC）， composite fungus with molasses group （FT）， and composite fungus with cellulase group （FX）. Each group was replicated three times， and after 30-day fermentation at room temperature， the samples were opened and sampled to determine their nutrient composition， fermentation quality and microbial diversity. The results showed that compared with the CK group， the crude protein （CP） and crude ash （Ash） contents in BC， FT and FX groups increased significantly， while the neutral detergent fiber （NDF） and acid detergent fiber （ADF） contents decreased significantly. The FX group had the highest contents of ammonia nitrogen （NH₃-N， 9.13%DM） and acetic acid （AA， 1.95%DM）. The Entropy Weight-TOPSIS evaluation indicated that the FX group had the best quality with a relative closeness degree （C_i） of 0.510. Microbial diversity analysis showed that BC， FT and FX groups significantly reduced community richness and diversity. At the phylum level， the dominant phylum in all groups was Bacillota， with the highest relative abundance in the FX group， followed by Pseudomonadota with the highest abundance in the CK group. At the genus level， the dominant genera in the CK group were mainly Lentilactobacillus， Sporolactobacillus， Clostridium， and Lactiplantibacillus， while the BC， FT and FX groups were dominated by Lentilactobacillus. In conclusion， the composite bacterial agent significantly improved the silage quality of corn stover and altered its microbial community structure， with the FX group （bacteria enzyme synergism） showing the best silage effect.

Corn straw  /  Silage  /  Bacterial enzyme synergism  /  Fermentation quality  /  Nutrient content  /  Microbial diversity