The invention relates to a low-voltage power distribution network power line carrier communication performance quantitative test system. The system comprises a physical layer transparent access device, a main node shielding box, a child node shielding box, a main node carrier communication unit, a child node carrier communication unit, a signal generation unit, a signal analysis unit and a switchcontrol unit. The signal analysis unit comprises a frequency spectrograph, an oscilloscope and a first power divider, wherein the output end of the first power divider is connected with the frequencyspectrograph and the oscilloscope. The switch control unit comprises an adjustable attenuator and a radio frequency switch connected with the adjustable attenuator in parallel. The power line carriercommunication performance quantitative test system further comprises a router and an industrial personal computer, and the router is controlled by the industrial personal computer and wirelessly controls other units of the test system. Compared with the prior art, the system has the advantages that the test result is more comprehensive, the accuracy is higher, the equipment reaction speed is higher during testing, wiring is not needed during system building, and a relatively pure electromagnetic environment is provided for the carrier communication unit.