Abstract: Since the past decade increasing interest has been taken in the use of trace fos-sits as paleoecological indicators, the influence of bioturbation upon sedimentaryprocesses and the nature interaction within the soft-bottom community. This paperbegins with a presentationof the behavioral characteristics and classification of tracefossils，and then a discussion of their use in paleoenviron m ental reconstruction.Trace fossils map be used to distingush marine from non-marine and transitionaldeposits. The most successful application of ichnologp to sedimentology is in theaspect of facies analyses and paleobathymetric zonation of marine deposits. Tracefossils can furnish valuable information concerning the general depositional proces-ses，the relative rate of deposition and erosion and the characteristics of current,bottom matter. The trace fossils assemblage of a deposit can be compared with bodyfossils and lithologicaI evidence so as to reconstruct a m odel of the ancient environ-ments.