Abstract: In this paper, the mechanism and calculation models of water mist technology, the determination method of water supply volume and technological features of this technology to control fire for cavern tank are introduced. This technology, besides the surface cooling mechanism, is to control or suppress fire through several functions in air phase cooling, oxygen insulation, heat radiation absorption and fire penetration. This technology, with low water volume, cost-effective, non-pollution and obvious result in fire control, is suitable to the fire control for cavern tank.