The utility model relates to a valve, specific novel check valve that the leakproofness is stronger that says so, which comprises the following components: a valve body, the both ends of valve body are provided with inhalant canal and exhalant canal, be provided with double -deck valve plate in the valve body, double -deck valve plate includes main board and second board, the one end of main board and the one end swing joint of second board just connect in the inhalant canal's of valve body inner chamber upper portion jointly, the other end setting of main board is in the inhalant canal lower part, and the other end setting of second board is in the lower part of exhalant canal. The utility model discloses the proposition of originality the structure of double -deck valve plate, realized the effect to the secondary seal of check valve, the pressure of exhalant canal to the main board can have been alleviated with sealing up inhalant canal and exhalant canal respectively to double -deck valve plate for the sealing performance of whole check valve strengthens greatly.