Abstract: The theory of seismic sedimentology is applied to Xujiahe Formation in YB area, Northeast Sichuan. First, constrained by primary sequence boundaries, the high-resolution sequence stratigraphic framework is automatically identified and traced through 3D phase expansion. Then the seismic events along the sequence stratigraphic interfaces are flattened through 3D Wheeler transformation. Thus sequence stratigraphic framework is transformed into chronostratigraphic framework and simultaneously seismic data is transformed into isochorn-strata data. The slices extracted from these data are used for analyzing sedimentary facies. Case studies show that this method can determine the spatial distribution and evolution of sedimentary facies, which can predict the geometry, distribution and evolution of reservoir and the promising targets for future exploration.