The invention provides a network timing IED time synchronization detection method based on physical layer time information. According to the method, time synchronization performance of a clock synchronization signal of a network timing IED communication port is detected according to a traceable conventional clock synchronization signal of a clock-source device and on the basis of the physical consistency degree of a network physical layer signal output by the IED communication port, time information carried by the network physical layer signal, and a clock synchronization signal of the clock-source device. The method confirms to the quantity transmission principle, and has the advantages of being physically displayable and traceable.