Abstract: The Jurassic in the West Sichuan Foreland Basin is continental detrital sedimentary strata, within which the recognizable sequence boundaries include uncomformity and erosional deposi-lion break, and lake-flooding surface. In order to overcome the limitation of these tow sequence boundaries in the continental strata studies, the authors introduce the concepts of the largest progradational surface and the largest lake-flooding surface. The
largest progradational surface is just the largest erosional surface or even the unconformity, and the largest retrograding surface is just coupled by the largest lake-flooding surface. Taking the system tracts as the basic consisted units within the sedimentary sequences，in the light of progradational system tracks and retro-grading system tracks，the authors divide the Jurassic of West Sichuan Foreland Basin into 8 sequences, which can be correlaled within the whole basin. Since the progradational system tracks represent the products during the period from weak to strong structural activity, and also because the development of delta sediments is one of the important criteria of the progradational system tracks, so the sequence subdivision scheme is of
significance to guide petroleum exploration.

Key words: West Sichuan, Jurassic, sequence stratigraphy, progradational surface, retrograding surface