In our daily lives, we enjoy the service of thousands of devices and systems that have made our lives easier and more comfortable. Electric fan is one of the most popular and used systems in developing countries like Bangladesh for its cost effectiveness and low power consumption. In the era of twenty-first century we expect all of our living and working systems will be intelligent when it will provide the service. We have developed a fuzzy inference system that effectively and intelligently controls the rotating speed of an electric fan according to the temperature of environment and its relative humidity. We used experimental data and verified the experimental data with different mathematical procedure to ensure that our result is well enough. We designed a simulation system to test the result but it can be easily implemented on hardware level, since fuzzy logic toolbox provides such facility.