Abstract: The project of Jurassic sedimentary facies division has systematically been made in Junggar basin by applying the modern sedimentology research method of sedimen-tary systems, system tract and sequence ana lysis, etc., and different periods of Jurassic sedimentary facies patterns have been established by adopting isochronal stratigra phicunit. Filling and evol u tion histbry of Junggar basin in Jurassic has been revea led by using both gentle slope and steep slope sedimentary system patterns. It is considered that the most favourable hyd roca rbon-generating places are melanocratic mudstone of half deep la-custrine facies to deep lacustrine facies (Middle Jurassic) as well as coal-seam in swamp environment of lake bay; the most favourable reservoir sand body developed in facies-change zone of flu vial facies and lake facies. The area of frequent alternate change for fluvial facies and lake facies, which is the most developed area of non-structural trap, is the most favourable for Jurassic oil and gas prospecting in Junggar basin.

Key words: Junggar basin, Jurassic, Sedimentary systems, Source bed, Sedimentary facies, Prospective area