Abstract: The recent IEEE 802.11ac adopted a novel multi-user access technique, which was the downlink multi-user MIMO (MU-MIMO) transmission. This was very different from the former IEEE 802.11 standard’s protocols. The MU-MIMO transmission technique in 802.11ac draft was studied and proposed some optimal designs. Finally, the performance of the IEEE 802.11ac MU-MIMO transmission schemes and gives the simulations. The simulation results show that the proposal transmission schemes can achieve gains of BER and throughput in theory and simulations.