Abstract: An automatic module switching system of a combined processing apparatus includes a chassis, a moving mechanism, a holding device, and multiple processing modules. The moving mechanism is driven to drive the holding device to move along a first moving direction and the holding device is driven to move along a second moving direction on the moving mechanism. The processing modules are detachably mounted onto the positioning sets of the hanging wall of the chassis and the holding device. The holding device drives the processing module thereon to move along a third moving direction. The combined processing apparatus can be scheduled to switch the processing modules automatically according user's needs, such that the combined processing apparatus can process in a manner that meets the user's needs. Cost for purchasing the plurality of processing machines can be saved and the problem of occupying much room can be also avoided.