Abstract: This paper proposes the two level network allocation vector scheme aiming to solve the problems caused by the employment of MU-MIMO and bandwidth expansion, the scheme proposed can not only solve the problems efficiently in conventional mechanism but also be simple and easy to implement, and can boost the system throughput significantly; on that basis, the paper proposes unequal bandwidth transmission scheme, which can not only solve the problem of bandwidth waste under multiple users mode but also further improve the system throughput. This paper analyzes the schemes proposed and obtains the throughput gains of single user mode and multipleuser mode. Finally, simulations are provided to verify the effectiveness of scheme proposed and the correctness of analytical results, from which to see that the scheme proposed can obtain throughput gains dramatically with the redundant time length in TXOP increasing.