The invention provides a flue gas recirculation-based wide load-wide coal deep denitrification system for a CFB (circulating fluidized bed) boiler. The system comprises the boiler, an SNCR (selective non-catalytic reduction) system, a primary air blower, a secondary air blower, an induced draft fan, a recirculation flue, a primary air recirculation adjusting valve, a secondary air recirculation adjusting valve and the like. One end of the recirculation flue is connected with an outlet of the induced draft fan, the other end is connected with an inlet of the primary air blower and an inlet of the secondary air blower by the aid of the primary air recirculation adjusting valve and the secondary air recirculation adjusting valve, low-temperature flue gas is led out of the outlet of the induced draft fan, the low-temperature flue gas with the proper flow is sent to different positions of a combustion chamber by the blowers through control by the adjusting valves, distribution of temperature fields in the boiler is optimized by fine controlling content of oxygen of primary air and content of oxygen of secondary air on the basis of SNCR, pollutant emission is reduced, and the CFB boiler can realize low emission of NOx under wide load-wide coal conditions.