The volcanic oil reservoirs hold a cumulative proven oil reserve of 520 million tons, accounting for 15.1% of the total proven reserves in the Xinjiang oilfield, positioning it as a crucial area for reserve growth and production enhancement. However, the exploitation of volcanic oil reservoirs using fractured horizontal wells faces a series of challenges, including rapid production decline, insufficient reservoir pressure maintenance, moderate to high water cut, limited connectivity of artificial hydraulic fractures, and significant well interference. These issues highlight the urgent requirement for optimizing and implementing an effective development strategy. The CO2 huff-n-puff process is a proved approach for enhanced oil recovery in unconventional oil reservoirs, but its performance and controlling factors remain poorly understood for volcanic oil reservoirs. In this study, the oil production response of the CO2 huff-n-puff process in the Carboniferous volcanic oil reservoir is investigated through geological modeling and reservoir numerical simulations, with sensitivity analyses revealing the key controlling factors. The numerical simulation results show that, the cumulative oil recovery performance after four operation cycles can be 14% higher than that of pressure depletion, and a cyclic injection quantity of 500 m3 in bottomhole pressure conditions with a soaking period of 15 days is feasible for field implementation. The findings of this study can offer valuable guidance for future field operations in similar volcanic oil reservoirs.