The invention relates to a sealing test device suitable for liquid hydrogen temperature zone, and belongs to the field of low temperature engineering and low temperature technologies. The test device comprises a steel pipe capable of moving up and down, a sleeve nut, a spherical joint, a welding tube nozzle, hexagonal bolts, hexagonal nuts, a cavity connecting steel pipe, a test Dewar top cover, a cylinder of a test Dewar heat-insulation layer, an upper cover flange of a test cavity, a test cavity body, an object to be tested, a low-temperature medium injection pipeline and a low-temperature medium emptying pipeline. The system can use low-temperature media as liquid nitrogen, liquid hydrogen, liquid helium and liquid neon, the object to be tested is placed in the test cavity to evaluate the reliability or physical and chemical properties of the object in the low temperature environment, and the sealing test system is simple in structure, economical and safe.