The invention relates to a system and method for testing a high-temperature superconducting cable through a direct-current power supply. The system comprises an industrial personal computer, a controller and power modules, wherein the industrial personal computer, the controller and the power modules are sequentially connected, and the controller and each power module are respectively provided with an interface. The method comprises that (1) the number of the power modules put into operation is judged according to an output current value; (2) an interrupt signal is judged before a current is output; (3) a current command is calculatedly output through a queue structure. According to the system and method for testing the high-temperature superconducting cable through the direct-current power supply, a multi-stage modularized parallel connection mode is adopted, the expansion on a power platform in future is facilitated, and when modules need adding to the system to conducting expanding, a control program is easy to change.