Abstract: The sedimentary mode of Gaotaizi reservoir in the Daan oilfield is established on the basis of a great deal of core data,logging data and identification of various facies,combined with regional geologic background. It is held that they be-long to meandering river delta sedimentary system,which developed delta front subfacies and prodelta subfacies. Delta front subfacies developed five microfacies as underwater distributary channel,interdistributary bay,mouth bar,distal barand frontal sheet sand. Based on this,and through horizontal correlation,in the paper the plane distribution of the sedimentary in every sublayer are drawn,and the distribution and variation of these microfacies are elaborated,which pro-vide important geologic evidence in the finding of the remaining oil.