The importance of drilling mud cooling is explained in terms of the storage temperature and pressure of gas hydrate. The structure, operational principle and design process of the mud cooling system for gas hydrate drilling are introduced with the field experiment. Of the system in the Chinese permafrost zone gas hydrate drilling. The experiment has proved that this system completely met the design requirements and for the first time successfully recovered the gas hydrate sample in the permafrost zone of the QinghaiTibetan plateau.