The well spacing in development area is from 500-600 meters in junior development phase to 100 meters even dozens of meters with the growth in oil exploration. The infill well pattern makes it possible to regain primitive distributing feature of sand bodies. By detailed core observation and description ,and applying well logging and every geologic information, the article makes careful research on sedimentary environment and sedimentary feature in research area; it also makes detailed dissection on large scale overlap channels of Putaohua Reservoir of Saertu Oilfield in Songliao Basin; it puts up sedimentary feature ,recognition method and sedimentary model about large scale overlap channel sand bodies. So it offers reference for the dissection of large scale overlap channel sand bodies in other districts and it also offers important theoretical basis for exploiting the remaining oil in sand bodies in large scale overlap channels.