Abstract: The marine air-conditioning is important equipment on board the ship. It created the comfortable and cosy surrounding for the crew in the working time and daily lives. The fresh air for the air condition system is essential to keep the crew watchful during the watch-keeping. What is more, the condition outside of the marine vessel is diverse, the self-adjustability of the marine air conditioning is not swift. Meanwhile, the air-conditioning unit is the main energy consumption. The reasonable operation of the marine air-conditioning can be energy-saving. The parameters of temperature and the carbon dioxide concentration in the air-conditioning room are the key factors for the air-conditioning control. Under the condition that the unit of the marine air conditioning is not altered, the fuzzy control method is applied to adjust the temperature and the carbon dioxide concentration in the air conditioned space. The fuzzy controller is designed and the program is written in this study. In this way, the comfort index is high and the energy is conserved. Compared with the general control method PID, the fuzzy control without the mathematical model is simple and precise. Taking the temperature difference, the difference variety ratio and the carbon dioxide concentration as the control parameters, the marine air-conditioning can create a cozy and comfortable space for the crew on board the ship.