Expound the existing modulation mode of the present wireless local area network.Directing at the problem that when single modulation method conveys data with high speed in the frequency selective fading channel,the system throughput will be declined and the efficiency of the spectrum will be lowered.Put forward the scheme that the OFDM sub-carrier will use differ ent modulation modes after dynamic groups by amplitude frequency response.Simulation results show that the scheme will lower the complexity of the system achievement,and can get a higher spectrum efficiency. Expound the existing modulation mode of the present wireless local area network. Directing at the problem that when single modulation method conveys data with high speed in the frequency selective fading channel, the system throughput will be declined and the efficiency of the spectrum will be lowered. Put forward the scheme that the OFDM sub-carrier will use differ ent modulation modes after dynamic groups by amplitude frequency response. Simulation results show that the scheme will lower the complexity of the system achievement, and can get a higher spectrum efficiency.