Abstract: A 38-day co-composting of rice straw and food waste experiment was carried out to investigate the effects of inoculation of composite bacterial agents at different periods on organic matter degradation, microbial enzyme activity, and functional genes in the co-composting of rice straw and food waste. In the earlier composting stage, microbial enzyme activity and the degradation of organic matter such as starch and protein, as well as the carbon degradation genes abundance, were significantly increased in the treatment A group inoculated with the composite bacterial agent during the first fermentation stage. In the later composting stage, the degradation rates of starch, protein, cellulose, and grease in the treatment B group inoculated with composite bacterial agents during the secondary fermentation stage were higher than those in the control and A groups. The protease and cellulase enzymes activities were increased by 14.14% and 31.01%, respectively, on the 25th day. Pearson's correlation analysis revealed a significant effect of temperature on protease and cellulase. Additionally, a positive correlation was observed between organic matter (OM) and degradation of starch (P<0.01), grease (P<0.01), and protein (P<0.05), which indicated that substantial changes were present in carbon and nitrogen components during composting, with significant protein degradation. The cdh gene abundance, responsible for encoding cellobiose dehydrogenase, showed significant correlations not only with cellulose degradation (P<0.01), but also with starch and grease degradation (P<0.01), suggesting that cdh gene abundance might be the gene most closely related to carbon degradation in food waste composting. The study showed that the inoculation of composite bacterial agents at different stages could enhance the microbial enzyme activity and carbon degradation gene abundance in the co-composting of straw and food waste, in which the inoculation of composite bacterial agents at the primary fermentation stage had a better promotion effect on the degradation of organic matter in the compost.