Abstract: Da'an paleochannel is located in the central fallen area of Song-Liao subsiding belt which formed in the Mesozoic and Cenozoic, where the earth's crust motion in the Quaternary period was mainly slow and successively extensive sedimentation. The cover layers consist of cretaceous sandstone forming in shallow sea, Tertiary system sandstone and mud stone and Quaternary system fragmental deposit stone, of which thickness is 143 m. That clay and mealy sand of Holocene were exposed to ground is in favor of constructing irrigation works. The area landform belongs to Songnen alluvial low plain. The altitude of terrace, which presented highland, is about 140 m. The main body of paleochannels, namely Nenjiang flood land, is generally below 132 m above sea level, which is even and widen. Natural grade from 1/5000 to 1/1000 is in favor of disposing constructing irrigation works. That the paleochannel nears to Nenjiang River and Moon Lake is convenient for using water, and the drainage can be discharged into Chagan Lake, then into the Nenjiang River,or discharged into the Nenjiang River at the Sanjiazi paleochannel pass.