Abstract: To solve the problem that the sublimation of dry-ice is too slow when it was used for fire prevention in goaf, a new device, dry-ice phase transformation generator, has been designed, which can improve the speed of dry-ice sublimation by the heat supply of water. In order to make the device successfully applied to underground coal mines, its performance was tested. Through the laboratory experiments, its hydraulic characteristics of the hot water supply part and gas production change were analyzed, the heat transfer was calculated, and the risk of copper tube freezing was evaluated. The results show that the device can produce CO2 stably and efficiently for 4 hours, and the water in the copper pipe does not have the risk of freezing under normal conditions. Finally, it is concluded that the device has good fire-fighting performance and can be used in goaf fire-fighting.