Data frame identification method and modulation method, relevant device and system

Disclosed by the embodiment of the present invention is an identification method and modulation method of data frame, relevant device and system, the method comprises: receiving OFDM PHY data frame; demodulating OFDM signal in the OFDM PHY data frame to obtain a first demodulated signal and a second demodulated signal; calculating real part signal energy and imaginary part signal energy on the basis of the first demodulated signal and the second demodulated signal; determining that the OFDM PHY data frame is 802.11ay data frame if the real part signal energy is determined to be greater than or equal to the imaginary signal part energy. The embodiment of the present invention is advantageous for improving the identification efficiency of the 802.11ay data frame.