A cold thermal energy storage system has been developed for HVAC. There are many ice-based cooling systems operating around the world. Ice slurry, which is a mixture of fine ice crystals and liquid water, is utilized in ice storage systems owing to its good flowability and large latent heat of fusion. For slurry ice production techniques, there are presently a number of commercially available ice slurry generators (e.g., Supercooled slurry ice generator, Scraper type generator, and Vacuum type generator, etc.). In the present study, a new method was developed to generate ice slurry without the deposition of an ice layer on a cooled surface. The basic components of the experimental apparatus is a cooling brine circulating loop, a high pressure pump, a valve, an aqueous solution flow loop containing the test section, which is made of transparent acrylic, and the associated instrumentation. This new method is based on freezing-point depression of the aqueous solution, which is maintained under high-pressure conditions. To control the timing for solidification and to generate ice slurry, we investigated the relationships among the pressure and temperature of the aqueous solution. The freezing phenomenon of the aqueous solution in the test section was observed in detail. As a result, we developed a new ice slurry generator based on the new method that controls the pressure and temperature of the aqueous solution. Experimental results showed that the characteristics of the ice slurry generation were closely related to the pressure and initial stage temperature of the test fluid. Finally, the optimum operation condition of the ice slurry generator based on visualization experiment was discussed.