The invention provides a supercritical hydrothermal 
combustion device suitable for high-
viscosity fuel. The supercritical hydrothermal 
combustion device suitable for the high-
viscosity fuel is mainlycomposed of an upper end cover, a middle end cover, a first 
combustion stabilization chamber body and a second 
combustion chamber body which are sequentially connected and assembled. The upper end cover is provided with a first-grade fuel inlet, a high-energy heating rod and a first-grade 
oxidizing agent inlet. The middle end cover is provided with a second-grade fuel inlet, a second-grade 
oxidizing agent inlet and a reactant first-grade 
spray nozzle. The reactant first-grade 
spray nozzle communicates with the first-grade fuel inlet. The inner wall of the first combustion stabilization chamberbody is a double-layer-spiral wall, the bottom end of the first combustion stabilization chamber body is provided with a second-grade 
spray nozzle communicating with the second-grade fuel inlet and the second-grade 
oxidizing agent inlet. The inner wall of the second 
combustion chamber main body is a double-spiral cooling wall, and the bottom end of the second 
combustion chamber main body is provided with an outlet hole group. Finally, a combustion stabilization chamber is formed between the first-grade spray 
nozzle and the second-grade spray 
nozzle. A combustion chamber is formed between thesecond-grade spray 
nozzle and the outlet hole group. A 
mixing chamber is formed between the outlet hole group and a bottom outlet of a reactor. The supercritical hydrothermal combustion device suitable for the high-
viscosity fuel directly generates steam in an oil layer, so that the problems of 
high energy consumption and heavy 
pollution caused in the 
steam injection process of a heavy oil thermalrecovery ground boiler are solved.