The invention belongs to the field of energy, and particularly relates to an oil shale circulating fluidized bed retorting method based on methane-rich mixed gas and an oil shale circulating fluidizedbed retorting system based on methane-rich mixed gas. According to the method, the activated mixed gas of methane-rich mixed gas and carbon dioxide is adopted as fluidizing gas, and by the way of heat exchange, the semi-coke of the fluidized retorting of oil shale sequentially heats a catalyst layer and a heat exchange gas chamber to promote the catalytic activation of the methane-rich mixed gasand carbon dioxide; after fluidized retorting product, except the semi-coke, undergoes gas-solid separation, condensing liquefaction and oil-water separation, shale oil, noncondensable gas and water are respectively obtained, solid particles which are separated out by gas-solid separation return into a retorting chamber for further reaction, and thereby the oil shale retorting conversion rate is increased. The activated mixed gas of the methane-rich mixed gas and carbon dioxide can be in sufficient contact with the oil shale, which is favorable for the combination between activated molecules and oil shale retorting free radicals, consequently, the yield of oil is increased, the hydropyrolysis cost is reduced, greenhouse gas emission is reduced, and the environment is improved; and catalystis easy to recycle and reuse. Operation is simple and convenient, and mass production is easy.