The structure is complicated in the block Bi123-124 of the Guchen oilfield, and the reservoir is controlled by the lithology and structure. The crossflow is very serious in the study area, and the adjustment of the injection and production is difficult. On the basis of the data of core, well log, grain size, we identify the signs of sedimentary facies, and study the micro-facies of the reservoir sedimentary facies. The result shows that the Ⅳ sandstone layer of the second member of He Formation has developed delta front subfacies deposit, which can be divided into six types of sedimentary microfacies and creeping turbidite sandbody. The sedimentary microfacies include subsea distributary channel, river flank, mouth bar, distal bar, front sheet sand and distributary inter channel. The shape and distribution and superposition of the reservoirs sand are analyzed, so we can find that the subsea distributary channel and mouth bar are the favorable facies belts of the study area. All of above proofs that the oilfield in the studied is controlled by the structure and lithology. The result of the study can provide geological basis for the next step of the adjustment of the exploration.