Abstract: In this paper, 11 samples of fluid inclusions from the Suowa formation in Esima area of Qiangtang basin were analyzed, including the fluorescence observation, micro?temperature and salinity measurement, etc. The results indicate that five periods of thermal fluid events took place in this Suowa reservoir, among which the second, third and fifth periods were related to the hydrocarbon accumulation in this area: the second and third periods were dominated by oil charging and the fifth by gas charging. Combined with the burial history analysis, it is concluded that there exist three periods of large?scale hydrocarbon accumulation processes, namely, in the end of Late Jurassic tothe early of Early Cretaceous (148.3×106~144.7×106 a), the early of Early Cretaceous (144.7×106~141.1×106 a) and the Middle Miocene(17.6×106~11.3×106 a)