This paper provide the performance comparison of the IEEE 802.11n and IEEE 802.11ac Wireless Local Area Network (WLAN). The IEEE 802.11ac protocol currently has been used widely. Network Simulator (NS-3) is used to simulate it. The advantages of the research using Network Simulator are shorter time to explore, low cost and flexibility on scenario developed. Our project analyzes and compares the 802.11ac and the 802.11n protocols. The goal of our project is to compare throughput between the IEEE 802.11 and IEEE 802.11ac using variety of Spatial Streams (SS), data rates and number of client. The parameters variation i.e. the number of clients, the index of the Modulation and Coding Set (MCS), load rates, Spatial Streams (SS) at the 802.11n (High Throughput MCS) (HtMcs) and the 802.11ac Very High Throughput MCS (VhtMcs). Result show that the throughput of the IEEE 802.11n is same as that of the IEEE 802.11ac in a bandwidth of 40 MHz, with a client and spatial streams of 1-4. Moreover, The throughput of the 802.11ac is higher than that of the IEEE 802.11n in the bandwidth of 40 MHz, and 2 clients (1-4SS).