A power line communication (PLC) multi-frequency protocol simulation platform based on NS-3 network simulator is proposed to deal with the lack of evaluation and verification environment for PLC protocol. Based on NS-3, PLC module is developed, which contains the physical layer, medium access control (MAC) layer and logic link control (LLC) layer functions. Based on the three-handshake of preambles, PLC module can support multi-frequency networking. Besides, the proposed PLC protocol simulation platform can suport for typical network topology and attenuation configuration, and could import measured attenuation and noise data. The test results shows that the proposed PLC multi-frequency protocol simulation platform could simulate and verfiry different MAC functions, key algorithms and parameters in different scenarios, and could evaluate nodes access probability, throughput, and latency performance, and so on, it is a powerful tool for the study of multi-frequency PLC protocol.