IEEE　802.11n　is　a　next-generation　wireless　WLAN　standard　which　can　support　a　MAC　data　throughput　over　100Mbps.　Frame　aggregation　mechanism　is　a　key　feature　at　the　MAC　layer　which　can　improve　the　efficiency　of　channel　utilization.　In　this　paper,　we　investigate　the　performance　of　video　transmission　over　IEEE　802.11n　with　frame　aggregation　mechanism.　We　derive　the　relationship　between　Subframe　size　and　bit　error　rate　and　the　relationship　between　retry　limit　and　packet　loss　rate,　which　can　be　easily　used　to　design　adaptive　scheme　for　video　transmission.　Simulation　results　shown　that　the　optimal　subframe　size　adaptively　to　channel　conditions　can　improve　the　throughput　but　has　little　effect　on　the　video　quality,　and　proper　retransmission　policy　can　significantly　improve　the　video　quality　without　increasing　the　end-to-end　delay.