The invention relates to a method and an apparatus for reducing the cyanogen content of coking wastewater. The apparatus comprises a regenerating tower, a circulating ammonia pump, a raw material ammonia water pipeline, an alkali tank, a 42% alkali pump and a 2.5-5% alkali pump; the regenerating tower is connected with a desulphurization lean solution pump, the outlet of the desulphurization lean solution pump is connected with the circulating ammonia water pump, and the circulating ammonia water pump is connected with a coke oven; one end of the raw material ammonia water pipeline is connected with the raw material ammonia water pump, the other end of the raw material ammonia water pipeline is connected with the alkali washing section of a desulfurization tower, and the raw material ammonia water pipeline is connected with the 42% alkali pump; and the bottom of the alkali washing section of the desulfurization tower is connected with the alkali tank, and the alkali tank is respectively connected with an ammonia distiller and the alkali washing section of the desulfurization tower through the 2.5-5% alkali pump. Raw material ammonia water substitutes distilled ammonia wastewater and is mixed with a concentrated alkali, and the obtained mixture is sent to the alkali washing section of the desulfurization tower in order to remove hydrogen sulfide and hydrogen cyanide. The stability of the ammonia water volume of the alkali washing section is guaranteed; and the ammonia content of the raw material ammonia water is high, so the raw material ammonia water has a better desulphurization effect than the distilled ammonia wastewater.