The invention discloses a water combustion process. The water combustion process is implemented on the basis of a water combustion boiler and includes steps of ventilation, ignition, steam feeding, combustion and heat release. Steam is decomposed into hydrogen and oxygen when in an environment with the temperature higher than 1200 DEG C, electrons can be released by atoms of combustion-supporting alloy at the high temperature of 1500 DEG C, and heat can be released, so that the hydrogen decomposed from the steam can be ignited, the oxygen can realize a combustion-supporting effect, the hydrogen can be sufficiently combusted to release a large quantity of heat, and the purpose of combusting water which is used as fuel to generate the heat is achieved. The water combustion process has the advantages that the water combustion process is applicable to power generation, heat supply, the industry and the agriculture, the water combustion boiler for implementing the water combustion process is applicable to modification projects for coal combustion boilers, gas combustion boilers and oil combustion boilers, the steam and other fuel can be jointly combusted in the water combustion boiler to generate the heat, and fifty percents of fuel can be saved on the premise that the same quantity of heat is supplied.