The ventilation systems are inadequate, the increase in the amount of carbon dioxide and carbon monoxide in the inner environment can damage human health. In addition, obtaining the level of external environment with excessive ventilation can lead to unnecessary energy consumption. In this study, a system that absorbs air from the environment using carbon dioxide, oxygen and carbon monoxide values in ambient air and controls the operation of the ventilation system that gives fresh air to the environment is designed with fuzzy logic method. The overall purpose of the system is to achieve the ideal ventilation level. Two separate ventilation valves were controlled at the same time with the fuzzy control system designed in the study. The fuzzy control system was created with MATLAB Fuzzy Logic Toolbox and the operating structure of the control system had analyzed.