The utility model belongs to the technical field of chemical plant waste heat utilization technique and specifically relates to a produce heating system of megaton methyl alcohol per year, realizes through setting up reasonable pipe network that energy cascade utilizes and waste heat recovery, including the boiler, take out out -of -the -way formula turbo generator set, the condensing formula of drawing gas turbo generator set, catch water, I level supply the female pipe of vapour, II level to supply the female pipe of vapour, III level to supply the female pipe of vapour, IV level to supply the female pipe of vapour, V level to supply the female pipe of vapour, by -pass valve. Compared with the prior art, the utility model, can make full use of the heat energy of high temperature high pressure steam, take out out -of -the -way formula turbo generator set, condensing formula turbo generator set that draws gas through one and has satisfied tertiary heating steam, has utilized the heat recovery steam of one -level again, it needs the outer cost that purchase the electricity to have reduced the chemical plant simultaneously, realizes the self -sufficient of power consumption.