The invention relates to a method for converting methanol or dimethyl ether into low-carbon olefin. The method mainly solves the problem of low yield of the low-carbon olefin in the prior art. The method comprises the following steps of: (a) making a raw material containing at least one of the methanol and the dimethyl ether in contact with a catalyst in a fluidized bed reactor to generate product flow comprising the low-carbon olefin, delivering the product flow to a separation working section, and simultaneously forming a to-be-generated catalyst; (b) delivering the to-be-generated catalyst to a stripper, delivering the to-be-generated catalyst to a regenerator for regenerating at the lower part of the fluidized bed reactor after stripping, and forming a regenerated catalyst; and (c) delivering the degassed regenerated catalyst to a lift pipe, making the regenerated catalyst in contact with a lift medium, and lifting the regenerated catalyst to the fluidized bed reactor, wherein the lift medium comprises at least one of oxygen-containing compound and hydrocarbon of over C4 separated in the separation working section, and the active index of the regenerated catalyst is more than 0.8. According to the technical scheme, the problem is well solved; and the method can be used for industrial production of the low-carbon olefin.