The utility model discloses a valve, which comprises a valve base, a valve plate in the valve base and a control case installed above the valve base and used in opening and closing the valve plate. The valve base is a corrugated tube structure made by rubber. Outer surface of the valve base is sleeved with an annular positioning sleeve which is connected with the control case. The annular positioning sleeve and the control case are made by plastic with metal net interlayer. Through the structure above, the valve base has retractility and flexibility. The valve can be easily and quickly installed without carrying out correction of concentricity even deflection emerges in axial line of the tube so as to improve working efficiency. Meanwhile, the valve base made by rubber, and annular positioning sleeve made by plastic and inner wall of the control case are provided with metal net interlayer, which large reduces weight and cost of the valve and simplifies transportation of the valve, in particular valve with big caliber.