The invention relates to a comprehensive recovery method of waste and old cathode charcoal block of an aluminium electrolytic tank, and belongs to the technical field of comprehensive utilization of industrial solid waste resources. The method is as below: crushing and grinding waste and old cathode charcoal block of the aluminium electrolytic tank at 200-400 DEG C, insulating, removing cyanide, conducting flotation separation on the material with cyanide removed to obtain carbon slag and electrolyte slag, heating the electrolyte slag at 550-800 DEG C to remove carbon impurities, so as to obtain an electrolyte powder, removing to soluble substances in the electrolyte slag by alkali leaching to obtain a carbon powder with high purity, and precipitating a mixture of cryolite and aluminium hydroxide form the alkali leaching liquid by CO2. The invention has the advantages of reasonable process design, simple process, high treatment efficiency, high recovery rate and recycling rate of each material and no secondary pollution, and is applicable to large-scale industrial application.