The invention provides an operation method of a PET wood-plastic composite manufacturing device, belongs to the technical field of composite preparation methods, and particularly relates to an operation method of a PET wood-plastic composite manufacturing device. The method is used for manufacturing PET wood-plastic composites with interlayer structures and comprises the steps that S1, a control device is powered on to be started, and a main extrusion device is started; S2, an auxiliary extrusion device is started; S3, prepared main materials are added into a feed hopper; S4, prepared auxiliary materials are added into an auxiliary feed hopper; and S5, operation for extrusion machining and post-machining is carried out. The device is provided with the control device, the main extrusion device, the auxiliary extrusion device and a mold head, wherein the main extrusion device and the auxiliary extrusion device are connected through the mold head. By adoption of the operation method of the PET wood-plastic composite manufacturing device, wood-plastic composites and products can be manufactured conveniently and efficiently.