The utility model discloses a double mechanical seal device sealing performance detects instrument belongs to mechanical maintenance technical field. This sealing performance measuring instrument includes: pressure device, connecting pipe, control valve, pressure indicating device, an adapting unit and the 2nd adapting unit, pressure device, connecting pipe and control valve are connected in order, the 2nd adapting unit's one end and control valve bond, the 2nd adapting unit's the other end is used for being connected with the seal fluid outlet of double mechanical seal device, an adapting unit's one end and pressure indicating device are connected, and an adapting unit's the other end is used for the sealed liquid access connection with the double mechanical seal device. It can detect its sealing performance before the installation of double mechanical seal device to utilize this sealing performance to detect the instrument, in time pinpoints the problems, does over again after avoiding installing.