Dung beetle serve as valuable indicators for studying environmental changes and as model systems for exploring ecosystem functionality. By analyzing the diversity and composition of gut microbiota in Catharsius molossus under starvation and refeeding conditions, this study investigates the effects of dietary states on the gut microbiota of these insects. Artificial rearing methods, along with 16S rRNA high-throughput sequencing and bioinformatics, were used to analyze Catharsius molossus gut microbiota under varying dietary conditions. The results indicate that at the phylum and genus levels, the gut microbiota of Catharsius molossus under refeeding conditions is more diverse than that under starvation conditions, with seven phyla and twenty-two genera showing significant differences (P < 0.05). In terms of functional prediction, the predicted functional genes of the gut microbiota were annotated to the KEGG database, revealing significant differences in thirty-two metabolic pathways at the third level (P < 0.05). Furthermore, it provides functional prediction information related to specific microbial taxa. Additionally, Dysgonomonas is speculated to participate in nitrogen fixation, and the gut microbiota of Catharsius molossus may potentially serve as a source of antimicrobial agents like anshanmycin. These findings provide novel insights into Coleoptera ecosystem microbial interactions and offer theoretical support for future applications.