Low-temperature thermostat based on low-temperature self-adjustment

A thermostat cold mass support assembly disclosed by the present invention comprises a thermostat bottom plate, a cold mass support supporting part and a base support, the cold mass supporting part is fixedly connected to the top of the base support through the thermostat bottom plate, and the cold mass supporting part comprises a cold mass support. A superconducting cavity and a superconducting magnet are installed on the cold mass support in a pre-offset mode, a low-temperature cold shrinkage amount is preset on the height of the cold mass support, and the base support is used for providing a horizontal installation plane for a thermostat bottom plate. According to the invention, the superconducting cavity and the superconducting magnet are installed in a pre-offset manner at normal temperature, so that the whole cold mass bracket assembly can be subjected to cold contraction at low temperature, and the cold mass bracket has a preset low-temperature cold contraction amount at the height, so that the cold ma