Optical filter is one of the most accurate and important elements in pure optical communication network which uses wavelength division multiplexing (WDM). This research includes studying Acousto Optic Tunable Filter (AOTF) in linear anisotropic medium, which depends on the interaction principle between optical waves and acoustic waves. This paper describes simulating and testing the AOTF in MATLAB/Simulink software which is a strong tool for simulating and designing various systems. We have achieved an AOTF model, and created special block which could be added to MATLAB Simulink Library. We have also evaluated the performance of this filter and its ability to select one wavelength between the set combined by WDM. Moreover, we have studied the effect of acoustic wave frequency, its velocity, the properties of the crystal used in manufacturing it, and other influent parameters, along the selected wavelength.