Abstract: A 3D printing technology-based processing apparatus and method includes a frame, an injection unit, and a molding unit. A melted polymer filler can be filled into a blind hole or a passageway of a 3D printed product to improve overall strength of the product. A 3D printed product having a mortise and tenon shaped mechanical engagement structure is disclosed. The printed product having the mortise and tenon shaped structure has higher tensile strength and shear strength. The present apparatus effectively resolves a problem of warped and deformed products due to an excessive temperature difference between the product and an environment during printing. The method uses an optimized printing process to reduce the fabrication processes of a support structure, reduce consumables required for building the structure, and improve the printed surface quality of the printed product.