Abstract: Linyi sag is a subsidiary negative structure element in Jiyang depression. This paper analyzes in detail the transporting and conducting system, time, mode and direction of secondary migration of oil and gas in the sag. The transporting and conducting system is consisted of sandstone layers, unconformities, faults and volcanic intrusions; migration modes are seepage flowing and shoving; and oil and gas migration obeys "centrifugal" regional migration law in the sag. The uplift zone, slop zone and inherited rift are favorable areas for progressive exploration and development.