In traditional 3D printing, the best method for creating overhanging structures is to add supporting materials; however, this often leads to an increase in costs and a decrease in printing efficiency. Therefore, a five-axis CNC machining technology is introduced in this paper, proposing an unsupported 3D printing method. Models requiring support structures were supported by an existing supporting surface by adding two degrees of freedom (rotation and swinging). Moreover, effectiveness of the proposed method was verified by experiment.