Abstract: Various kinds of heavy crude oil is widespread in the Tarim Basin, especially in marine oxidized residual oceans where its distribution is to a considerable scale. In this paper,geochemical indexes are used to estimate the percentage of crude oil losses so as to find out about the accumulation scales of paleo-pools and to provide reliable data for the hydrocarbon reserve calculation of the basin. Heavy crude oil plays an active role in searching other types of accompanying pools or useful mineral resources together with its forming reasons and periods.