The invention provides a dynamic seal test device for cryogenic fluid medium. The dynamic seal test device includes stator unit, rotor unit, slipway, servo motor unit and sensors. The tested seal is installed inside the stator, and the thermal insulation stator and vacuum rotor together form a dynamic seal test structure. The seals and shaft sleeves can be flexibly replaced, which is beneficial to study the influence of different seal types, structure, and seal land configurations on the sealing performance. The servo motor provides power for the rotor and controls the rotation speed. The device greatly improves the thermal insulation capacity to avoid the gasification for the cryogenic fluid medium induced by the heat transfer from environment so that ensuring the stability of the test device.