The invention belongs to the technical field of plastic mold machining, particularly relates to a multi-angle plastic mold surface milling device and a plastic mold machining process, and aims at solving the problems that in the prior art, fixed milling can only be conducted at one angle, use is very inconvenient, the workload of workers is heavy, and the milling efficiency is extremely affected. In order to solve the problems, the device technically comprises a base, a box body is fixedly connected to the top of the base, a milling cavity, a driving cavity and two transmission cavities are formed in the box body, and the milling cavity is located right above the driving cavity. According to the device, through cooperation of a planet gear, a sun gear and a tension pulley, the angle adjusting effect cannot be affected while the height is adjusted, the whole structure is simple, the parts are ingeniously matched, operation is convenient, a mole can be adjusted at any height and angle, the practicability is greatly improved, and therefore the milling efficiency is improved.