Abstract: The southwest depression in Tarim Basin is one of principal prospect area in it. This paper presents the source rock evaluation of its Carboniferous—Lower Permian,Middle—Lower Jurassic,Upper Cretaceous—Paleogene and Miocene layer by layer,with respect to sedimentary characteristic,abundance and type of organic matter,maturity and thermal alteration etc,It is recognized that the Carboniferous—Lower Permian could be a sequence of good source rocks with better source potentialities,In spite of reaching highly matured stage for mast part of the area,there has still been in non—mature to low mature stages near foot wall of Selibuya fault and upward Maigaiti stope. These should be as main targets for mate recent prospecting,of which the Middle-Lower Jurassic be a real source rock with some source potentialities; the Upper Cretaceous—Paleogene a source rock with poor ones; while the Miocene a more poor source rock to non--source rock.

Key words: Tarin Basin, Southwest depression, Source rock evaluation, Exploration direction