An innovative clathrate hydrate cool storage system and its performance in the air conditioning cool storage application are presented. This system consists of a clathrate hydrate storage vessel, in which there is a high-efficient inner-placed heat exchanger, and an outsideplaced small rotating crystallizer. In this configuration, clathrate hydrates can be formed effectively and thermal energy can be released and stored in high efficiency. The laboratory test of the system was performed, and it is shown that it has an excellent performance for cold energy storage at temperature about 8°C.