The utility model discloses a special thrown-in device for a compensating capacitor, which is formed by that a synchronizing signal circuit, a pre-charged circuit, a control circuit and a trigger system power supply are respectively connected with a power supply, wherein the control circuit is connected with the synchronizing signal circuit; the output ends of the synchronizing signal circuit and the pre-charged circuit are thrown in the capacitor. The synchronizing signal circuit is connected with a starting-isolating circuit through a shaping circuit, a negater circuit, a separated positive impulse circuit and a starting-triggering circuit. The utility model can restrict the inrush current in switching-on to zero, so that the capacitor directly goes into the operating current state so as to reduce attack to equipment and supply lines, decrease the public hazard for electric networks, prolong the service life of electric networks, and raise the current supply quality. With a reliable design, the compensating capacitor can ensure the on-time throw-in during equalization of electric voltage. The larger the throw-in capacitance of the capacitor is, the more the capacity for inrush current restricting of this device is embodied. After the voltage level of controllable silicon is raised, the utility model can still adapt the throw-in work of the high-voltage capacitor, just under the condition that the simultaneous triggering circuit is properly adjusted.