Natural gas hydrate(NGH) is also known as combustible ice. It is widely distributed under the continental shelves, oceanic slope areas and continental permafrost horizons with immense reserves, so it is likely to be one of the most important potential energy in the future. NGH research and development has been carried out abundantly all over the world, but up to now, NGH commercial exploitation hasn't been realized yet. In this paper, patent statistics and analysis were carried out on the main technical pro...