A partial discharge detecting system includes a partial discharge detecting device to generate a reference frequency signal, to detect a partial discharge pulse signal, and to convert the detected partial discharge pulse signal into a partial discharge digital signal, a main processor to synchronize the partial discharge digital signal, based on a zero-phase point of the reference frequency signal, to extract effective data from the synchronized partial discharge digital signal, and to store the extracted effective data, and an energy harvesting power supply device to supply power to the partial discharge detecting device and the main processor.