First, seismic data are used to the external form of cretaceous city group of pear trees rift sedimentary strata are divided into blocks, hummocky, lenticular, filling phase, sheet and mixed and disorderly equal to six types, in combination with characteristics of amplitude, frequency and continuity properties will be further subdivided into 9 kinds of seismic facies; Then use of coring well core features, sedimentary structure, grain size probability curve characteristics, C - M figure and well log data to determine the depositional characteristics of the typical Wells in the study area, the city group of the upper as braided river delta facies, lower mainly fan-delta facies, local development as the sublacustrine fan facies, adopt the combination of well-earthquake research method to establish the corresponding relationship between the seismic facies and sedimentary facies in the study area, and research the division of sedimentary facies this region.