The invention discloses a method for adjusting the air-fuel ratio of an annealing furnace. The method comprises the steps that the load mode of a normal work area is set as the automatic mode and theload mode of the area to be adjusted is set the manual mode; the number of nozzles in the area to be adjusted is N; the N-1th first differential pressure value delta P between flowmeters in turn of natural gas hole plates on the N nozzles can be measured, and the first average pressure difference delta P1 of the N-1th first differential pressure value delta P and the first average layer pressure difference delta P1' in the P layer nozzles are calculated; first to-be-adjusted nozzles when the N-1th first differential pressure value delta P is out of the range of delta P1+/-0.1 mbar is determined; the first average layer pressure difference delta P1' and the first average pressure difference delta P1 are compared, the first to-be-adjusted nozzle layer with delta P1' larger than delta P1 andthe second to-be-adjusted nozzle layer with delta P1' smaller than delta P1 which are adjusted in sequence are determined and are subjected to primary adjusting. The technical effects of sufficientlycombusting the fuel, and reducing pollution of black smoke, NOx and SOx to the environment are achieved.