Dealt with accumulation timing and hydrocarbon filling history, petroleum accumulation geochronology is a frontier field in modern petroleum geology, which has made great progress since 1980s when reservoir geochemistry, fluid inclusion analysis, isotopic dating, oil/gas-water contact retrospecting and other methods or technologies were introduced into studies of geochronology of petroleum accumulation and filling history. Now many methods including trap timing, hydrocarbon generation and expulsion history analysis, saturated/dew-point pressure method, reservoir geochemistry, hydrocarbon inclusion, K/Ar isotopic dating of authigenic illites, and oil/gas-water contact retrospection have been developed to determine the geochronology of hydrocarbon accumulation. These methods, particularly the fluid inclusion analysis and K-Ar dating of reservoir's authigenic illites, have transformed geochronological studies of petroleum accumulation from qualitative to quantitative, from relative ages to absolute ones and from macroscopic to microscopic. And combinations of indirect with direct studies, macroscopic with microscopic studies and qualitative with quantitative timing have become the important trend of petroleum accumulation geochronology, which is particularly necessary to geochronological study of accumulation and hydrocarbon filling history of complex basins. Still, application and problems of each methods of accumulation timing are discussed in this paper. And two problems are particularly emphasized: one is the re-homogenization of the original homogenized temperature of fluid inclusion, which may give rise to a measured temperature value higher than that when the hydrocarbon entered the reservoirs; the other is the systematic sampling of authigenic illites, which is considered to be extremely important when K/Ar dating of illites is used to determine the filling time of hydrocarbon. 