The invention discloses a low-voltage orthogonal frequency division multiplexing (OFDM) carrier physical layer communication performance detecting system which is used for detecting emission performance indexes and receiving performance indexes of a low-voltage OFDM carrier physical layer. The detecting system comprises a signal isolation device, a standard carrier sending device, a carrier to be detected sending device, a carrier to be detected receiving device, a standard 50 omega impedance power network, a coupling circuit, two mixers, two adjustable attenuators, a white gaussian noise generator, a line impedance stabilizing network, a programmable logic controller (PLC) demodulation device, an alternating current power meter, a 220V alternating current power source, a signal generator, a network analyzer, a spectrum analyzer, a channel simulator, a signal analyzer and a computer. According to the technical characteristics of low-voltage power line carrier communication of an OFDM modulation mode, the detecting system is capable of conducting detailed test to the main performance indexes of the communication mode, the testing process is speedy, system conformability is high, system manufacturing cost is low, and space and labor cost are saved.