NOVELTY - Coking wastewater is pretreated, pyrolyzed, and catalytically decomposed, and waste heat is recycled. Pretreatment is carried out by filtering such that the content of suspended substance is reduced to 70 mg/l or less, and preheating to 80-95 degrees C. Pyrolysis is carried out by contacting the pretreated wastewater in a furnace with high-temperature coke, heating, and evaporating wastewater for decomposing organic matter into gas containing hydrogen, methane, and carbon monoxide, and decomposing partial inorganic ammonia into gas containing ammonia.    USE - Treatment of coking wastewater.    ADVANTAGE - The method makes full use of heat of high-temperature coke, processes coking wastewater while cooling high-temperature coke, prevents environmental pollution, and enables effective usage of energy resources.    DETAILED DESCRIPTION - Coking wastewater is pretreated, pyrolyzed, and catalytically decomposed, and waste heat is recycled. Pretreatment is carried out by filtering using a filter such that the content of suspended substance is reduced to 70 mg/l or less, and preheating to 80-95 degrees C using a preheater. Pyrolysis is carried out by contacting the pretreated wastewater in a furnace with high-temperature coke at 950-1050 degrees C, heating, and evaporating wastewater for decomposing organic matter into gas containing hydrogen, methane, and carbon monoxide, and decomposing partial inorganic ammonia into gas containing ammonia. Catalytic decomposition is obtained by dedusting pyrolyzed mixed gas at 800-900 degrees C using a dust collector, supplying to a degradation reactor, decomposing non-pyrolyzed organic matter into gas containing hydrogen, methane, and carbon monoxide in the presence of a catalyst, and decomposing ammonia into nitrogen and hydrogen. Waste heat recovery is carried out by exchanging heat with respect to pyrolysis gas and waste heat boiler for reducing the temperature to 150-200 degrees C, supplied to a preheater for exchanging heat with wastewater after filtration, condensing portion of gas liquid water, which is output, and inputting rest gas to a gas pipe.