The invention discloses a thermal deformation control device of a multiple-degree-of-freedom spatial structure in a brazing high-temperature environment. The thermal deformation control device comprises a base, locating blocks, locating forcing screws, connecting screws and an auxiliary profiling press block. Peripheral equipment comprises a guide device to be welded and a startup spraying pipe tobe welded. The guide device is fixed to the base after angular locating is conducted on the guide device. The locating blocks are fixedly connected to the base through the connecting screws. The locating forcing screws pass through threaded through holes formed in the locating blocks, point to the direction of thermal deformation of the startup spraying pipe and tightly press the auxiliary profiling press block on the surface of the startup spraying pipe. The pressing force is applied in the normal directions of the excircle surfaces, close to matched portions, of two branch-shaped pipe portions of a workpiece through the locating forcing screws and the auxiliary profiling press block, and therefore the purpose of controlling thermal deformation is achieved. By the adoption of the thermaldeformation control device of the multiple-degree-of-freedom spatial structure, the phenomenon that due to thermal deformation, the gap of a brazing seam is enlarged in the high-temperature environment is avoided, then the phenomenon that the incomplete-penetration defect exists is avoided, and the brazing quality is substantially improved.