Abstract: Chengdao Oilfield is located in a neritic area of the southwest Bohai Sea, and it is a large drape structure over buried hills. With the development of Chengdao Oilfield, formation shortfall was very serious and formation leaking in the course of operating was a difficult problem in protecting formation. This paper introduced a new technology about formation protection-downhole bidirectional flow valve, and elaborated its structure, principle and effect on formation protection.