The invention provides a pure oxygen process gas combustor. The structural is a ring sleeve type, and an oxygen spray gun is installed in an oxygen spray gun chamber of a fuel gas spray gun through a flange. The fuel gas spray gun is installed in a combustion air pipeline of an air spray gun through a flange. The air spray gun is connected to the center of a process gas spray gun which is formed by connecting a process gas splitter and a process gas rotational flow device in series through a flange. The process gas rotational flow device, a mixer and a combustor end plate are connected together in series through flanges. A liner is installed on the combustor end plate through anchoring nails, and the outside of the mixer is sleeved with the liner, so that a thermal protection structure is formed, and an accessory connector is welded to the combustor end plate and penetrates through the liner. The modularized design is adopted for the combustor, each component achieves a single function, and changes of functional parameters of the combustor can be achieved through replacing one component. The pure oxygen process gas combustor can be adjusted according to technological conditions, and the 21%-99.5% adjustment range of combustion improver oxygen content is achieved.