On the basis of a new irreversible three-heat-source refrigerator model, an ecological optimization criterion is proposed for the best mode of operation of the refrigerators, which consists of maximizing a function representing the best compromise between the cooling rate and entropy production rate. We investigate the ecological optimization performance and derive the optimal cooling rate, coefficient of performance and entropy production rate for the refrigerators. Moreover, there are some advantages in using the ecological optimization criterion; it is especially beneficial for determining the reasonable use of energy and protecting the ecological environment. The conclusions obtained here are of importance in the optimal design and reasonable use of the energy of real three-heat-source refrigerators, such as absorption refrigerators, adsorption refrigerators, and so on.