A method for the coal gasification and the quick co-production of activated carbon belongs to the field of chemistry and chemical engineering, and is characterized in that dry coal powder or carbonous organic substances are taken as raw materials, air or the mixture of oxygen and water vapour is taken as a gasifying agent, the ratio of oxygen to coal is adjusted within the range from 0.3 to 0.58 Nm<3>/kg, the ratio of vapor to coal is adjusted within the range from 0.01 to 0.5 kg/kg, a co-production device is operated under the condition that the gasification reaction temperature is 1200-1400 DEG C and the operating pressure is 0.1-4.0 Mpa, and 75-90% of organic compositions in the dry coal powder or the carbonous organic substances can be converted into coal gas; the high-temperature coal gas from the co-production device is subjected to temperature reduction by a waste heat boiler and gas-solid separation by a dust remover, so as to obtain semi-finished activated carbon; finally, the semi-finished activated carbon is subjected to acid pickling, wet floatation and drying, so as to obtain the co-production activated carbon. According to the invention, the activated carbon product obtained by adopting the method has an advanced mesopore structure and excellent liquid phase adsorption and decoloration performance, the adsorbing and purifying effects to organic substances in water are superior to those of high-priced activated carbon products prepared by adopting certain traditional methods, no pollution is generated in the production, and the efficiency is high, so that the method is environment-friendly, and can be used for producing activated carbon in a clean manner.