During the last decade, water mist fire protection technologies have always been the hotspot in world safty field. Being the large consumer of Halon 1301 and Halon 1211 primarily, navies of most countries in the world felt more enthusiasm about it. US Navy, Royal Navy and other navies have undertaken an extensive study of water mist for fire protection applications aboard ship, especially in machinery spaces. And the results of the testing and theoretic study conducted by them are encouraging. Their study will be summarized in this paper, the purpose of this paper is twofold： to introduce their study to the fire protection workers in China and to provide a reference to China Navy in this field.