The invention discloses a method and a device for inhibiting generation of dioxin from incineration flue gas. The method comprises the steps of controlled cooling and quenching process. Flue gas with the temperature higher than 1100 DEG C from an incinerator is cooled to 600 DEG C by a way of waste heat recovery, through the power of an induced draft fan and the function of a distribution plate, an inert carrier in a spray-fluidization quenching tower is in a fluidization state, meanwhile cooling water is continuously sprayed into the tower; by utilizing the characteristic of high heat transfer efficiency of a fluidized bed, the incineration flue gas is instantly cooled to below 200 DEG C from 600 DEG C in less than 0.1s to inhibit the resynthesis of the dioxin. The method and the device provided by the invention have the characteristics of controllable quenching time and temperature, good quenching effect, non-generation of waste solids and waste water, and the like, are applicable to the purification of the incineration flue gas of various wastes, and realize the emission reduction of the dioxin.