A partial automatic beveling machine for weld joints of large-diameter thick-walled pipelines comprises a base, an axial support plate, a circumferential support plate, a radial support plate and transmission mechanisms, wherein a bottom plate is fixed to the base, axial guide rails are fixed at the two sides of the bottom plate, one transmission mechanism is fixed in the middle of the bottom plate, sliders are mounted on a bottom side plate of the axial support plate, the sliders are movably connected to the axial guide rails, circumferential guide rails are mounted on a side plate of the axial support plate, another transmission mechanism is fixed in the middle of the side plate of the axial support plate, sliders mounted at the two sides of the back of the circumferential support plate are movably connected to the circumferential guide rails, two parallel radial guide rails are longitudinally fixed to the circumferential support plate, dovetail sliders mounted on the back of the radial support plate are movably connected to the radial guide rails, and a main shaft driving motor is fixed to the front of the radial support plate through a pressing block. The partial automatic beveling machine can realize partial cutting on the weld joints of the large-diameter thick-walled pipelines, can realize the two functions of clearing flaws and machining bevels in the one-step machining process, is high in practicability and is suitable for the partial restoring work of the weld joints of various large-diameter thick-walled pipelines.