As China has gradually become the largest energy consumer and carbon emitter, the efficient utilization of CO_2 has become an important means in realizing the "dual carbon" strategy. Microbial catalytic reduction of CO_2 offers a low-cost solution for simultaneous green hydrogen storage and CO_2 conversion and utilization. This paper focuses on the development of CO_2 dry biomethanization process, and conducts experiments to identify the key factors affecting the conversion rate and mierobial community structure. The results showed that maintaining a temperature of 35 ℃, employing an optimal H_2/CO_2 feed ratio of 4 : 1 , and implementing a 6-day soaking period for the nutrient solution in an anaerobic dry reactor filled with carbon sponge are critical for enhancing the conversion rate. Additionally, microbes at the end of the soaking cycle were sequenced and analyzed by high-throughput sequeneing technology. The dry reactor exhibited dominance by anaerobic hydrogen-consuming methanogens, particularly at the genus level with Metanobacterium and Metaosaeta being prevalent. Moreover, the bacterial community displayed relatively high levels of Aconobacterium and Mesotoga. The investigation identified key factors influencing the conversion rate and microbial community structure, thereby enhancing the theoretical foundation and technical assistance for microbial methane production.