Abstract: The concept of oil source abundance index is presented by combining organic abundance of source rock with geological analysis, and applied in Southwest depression of Tarim basin. It is suggested that Miocene and Upper Cretaceous-Paleogene can generate few or no hydrocarbons dark mudstone in Mid - Lower Jurassic, and dark carbonate rock in Carboniferous - Lower Permian and Cambrian-Ordovician have relatively higher hydrocarbon generating potential, and argillaceous rock of Palaeozoic can generate no hydrocarbon.

Key words: Tarim basin, Southwest depression, Source rock evaluation, Organic matter abundance