A process planning apparatus based on augmented reality (AR) includes: a camera set capturing color and depth images of a processing machine and a probe operated by a human user in a real scene; a processor, which is signal-connected to the camera set and the processing machine, creates spatial intelligences for motion planning of the probe operated by the human user in an AR environment that combines a virtual workpiece with the real scene, and generates instructional data from the spatial intelligences to guide the human user to operate the probe to produce machine motion data for a manufacturing task; and an output interface, which is signal-connected to the processor and outputs scene data, the virtual workpiece and the instructional data to the human user.