The invention discloses a self-field critical current test device under the stretching of a high-temperature superconducting belt material. The self-field critical current test device comprises a force applying mechanism, a motion pull rod, two current leads and a sample holder. A servo motor is installed in a support frame. A lead screw is mounted on the servo motor. A motion slide block is fixedly connected to the lower end of the lead screw. The self-field critical current test device is suitable for a critical current test experiment under the mechanical tension of the high-temperature superconducting belt material immersed in liquid nitrogen or liquid helium. The structure of the movable end of the sample holder is introduced to ensure that a sample is not affected by the thermal expansion property of a sample holder material, so that the initial tensile stress of the sample in a low-temperature environment is basically zero, thereby providing a reliable platform for accurately evaluating the mechanical properties of the high-temperature superconducting belt material. Further, a protective block structure is configured to ensure that the sample is not damaged during an installation process, reduce human factors, and improve operability. A critical current test mechanism is introduced to provide a valuable basis for the mechanics-critical current performance study of the high-temperature superconducting belt material.