The invention relates to the technical field of industrial boilers, in particular to an alcohol-based fuel boiler combustion system. The alcohol-based fuel boiler combustion system comprises a boiler,a heat preservation furnace, an automatic gas inlet system and an automatic feeding system; and tail gas of the boiler passes through an oxygen content detection system and then enters the heat preservation furnace to be heated, a heating pipeline is arranged in the heat preservation furnace, water in the heating pipeline is preheated through the tail gas and then enters the boiler, a water temperature detecting system is arranged at a water outlet of the heat preservation furnace, and the automatic gas inlet system and the automatic feeding system are connected with a hearth of the boiler. The alcohol-based fuel boiler combustion system has the priorities that the combustion efficiency is fully improved through full mixing of fuel and air; combustion of the fuel is reduced by utilizing the heat radiation effect of an iron-chromium-aluminum mesh, and energy sources are saved; remaining energy of the tail gas is reasonably utilized, the water entering the boiler is preheated in advance, and heat energy waste is reduced; and automatic operation of the whole filter boiler is achieved by utilizing an automatic detection and operating system of all the parts, the gas inlet amount and the feeding amount in the hearth are reasonably controlled, and thus the efficient energy-saving purpose is achieved.