The invention discloses an active space vehicle potential control system based on energy conversion. The active space vehicle potential control system comprises an upper collector, a lower collector, an electric energy conversion storage and a detection unit, wherein the electric energy conversion storage and the detection unit are arranged between the upper collector and the lower collector, the electric energy conversion storage is connected with a load (or effective load), and the upper collector and the lower collector are respectively and electrically connected and arranged on two parts large in potential difference of a space vehicle. When the detection unit detects the potential difference of the two collectors, whether a potential difference signal reaches a certain potential difference or not through a power management system. When the potential difference signal reaches the certain potential difference, energy conversion is enabled to charge the electric energy conversion storage. When the potential is reduced to a certain potential, charging is stopped, and it is achieved that the potential of the space vehicle is reduced to a safety threshold. Charging charge is led out through the space vehicle parts different in potential and serving as the two collectors for energy storage and charging and is reduced to be below the safety threshold, the discharging risk is reduced, and meanwhile energy with the magnitude of 10W can be obtained.