Abstract: Wireless is quickly spreading into many new applications. The performance optimization is a key requirement in designing and operation of the WLAN. In this study the performance optimization methods have been presented using an advanced network simulator, OPNET modeler. WLAN performance optimization has been shown via a series of simulation tests with different parameters include RTS/CTS threshold, fragmentation threshold and data rate. The simulation results are presented showing satisfactory WLAN performance when the environment parameters are accurately tuned.