The power output of a wind turbine is directly proportional to the cube of the wind velocity. Even a marginal increase of wind velocity can result in exponential growth in power output. A Diffuser Augmented Wind Turbine (DAWT) is an improved version of ordinary wind turbine. With the help of diffusers, vortices are generated to form pressure difference and increase the wind velocity striking the rotor blades. The wind velocity enhancement depends on the geometry of the diffuser. This paper studies the impact of altering the brim angle of the diffuser on the diffuser efficiency and the power output. Four diffuser designs are generated with bring angles of 90, 75, 60 and 45 degrees and are analysed using flow simulation tool in SOLIDWORKS 2018 software. The best design with the most efficient brim angle can be identified from the result of analysis.