The invention provides a method and a device for processing splayed radially-distributed threaded holes in a cam part. The method comprises the following steps that (1) the cam part is located and clamped, the relative positions of the threaded holes are determined according to the geometrical relationships between a processed hole and a location surface of the cam part and between the processed hole and a location hole of the cam part, and one of the splayed radially-distributed threaded holes is formed in the rotation center of a lathe at first; (2) the center lines of the splayed radially-distributed threaded holes are lengthened, the lengthened center lines are crossed at one point, the point is used as an indexing center, and the other threaded hole is formed in the rotation center of the lathe through rotary indexing; and (3) final processing of the two threaded holes is completed by the numerical control lathe. The method and the device are suitable for field production, corresponding mounting requirements are given out according to different sizes of the parts, and the device is mounted on the numerical control lathe for completing related processing.