Volcanic rocks hydrocarbon reservoirs is an important type of unconventional oil and gas reservoirs. And the type of hydrocarbon reservoirs exhibit complex geological characteristics and diverse accumulation mechanisms, making them challenging to study. And very few work on the hydrocarbon accumulation period in Permian volcanic reservoirs in the western Sichuan Basin have been done. Therefore,we conduct comprehensive research and divide the hydrocarbon accumulation period.Methods: In order to determine the hydrocarbon accumulation period, we apply a method to Permian volcanic reservoirs in the western Sichuan Basin. And the method include petrographic analysis of fluid inclusions, fluorescence microanalysis and homogenization temperature measurement. This method has passed a lot of tests and is highly feasible and progressive.Results and Conclusions: The method of fluid inclusions analysis has been successfully applied to Permian volcanic reservoirs in the western Sichuan Basin. And the main two hydrocarbon accumulation periods are divided. The main host minerals of the inclusions are quartz and calcite filled in the pores, and the inclusions are distributed in bands or groups. The hydrocarbon inclusions are relatively mature and appear blue and white under fluorescence.The homogenization temperature of inclusions showed unimodal characteristics, and the peaks was 110~130℃ and 150~170℃.Combined with the analysis of the burial and thermal evolution history of the study area, the Permian volcanic reservoirs in the western Sichuan Basin have experienced hydrocarbon accumulation periods, the period occurred in the Early Triassic (245~243 Ma) and Middle Triassic(224~230 Ma).