Abstract: In this paper we analysis the main causes for the throughput bottleneck in the conventional Wireless Local Area Networks standard, and then study the principle of frame aggregation mechanism for 802.11n, and finally propose an adaptive frame aggregation mechanism. Simulation results show that the frame aggregation mechanism can reduce overhead of frame header and network delay, and improve the channel utilization, and the presented frame aggregation mechanism can also optimize the performance of system by dynamically selecting the subframe size and retry times according to the channel condition.