Shale gas in America mostly comes from thermogenic marine shales, and gas shales mainly distribute in Devonian and Carboniferous of Foreland and Craton basins, while the buried depth is 1 500~3 500 m. Shales in China include 3 types: marine, transitional and lacustrine. Marine shales basically distribute in the lower Paleozoic of Aulacogen and Craton basins;organic-rich concentrated parts are steady-going,and thermal maturity phase and gas content are high,so the explorational prospect is the best. Transitional shales mostly distribute in Carboniferous-Jurassic of Foreland and Craton basins;there is no obvious organic-rich concentrated part, and gas content changes greatly, so the explorational potential needs to be proved. Lacustrine shales typically distribute in Mesozoic and Cenozoic of rift and Craton basins;organic-rich concentrated parts are thick and stable, and explorational potential is probably great in center of depression which reaches generating gas stage.It is forecast that shale gas exploration will take a long time and output will be 50 billion~60 billion m3 in the future.