A new type of energy efficiency control method for fan-coil unit is presented. By introducing the conception of duty ratio into electric valve control, the cooling and dehumidifying capacity of fan-coil unit is fully utilized. By means of Mamdani type fuzzy rule and the Method of Functioning-fuzzy-subset Inference, duty ratio of valve and fan speed signal are identified according to deviation and deviation change of room temperature. It is shown that presented method could achieve at least 30% energy saving than traditional control method as well as a preferable room temperature control effect.