Abstract: In the thermal vacuum test, a large number of cables are connected to the communication satellite through a flange outside the space environmental simulator. A part of the cables would work beyond the normal temperature range, which may lead to undesirable phase jumps. To solve this problem, a new type of cables temperature control device is proposed. With it, the centralized temperature control of the cables in complex vacuum cryogenic environment is realized. In the thermal vacuum test of a new-generation communications satellite, the temperature of the related cables is controlled within a range of 40 ℃±5 ℃, and the temperature difference of a single cable along its path is kept within ±3 ℃. Under the controlled temperature, the requirements of timing and phase of the satellite payload is guaranteed, and therefore the accuracy of the ground testing is also improved.