This research is mainly on developing pencil sharpener with the following functions:First, grasp the pencil automatically;Second, cut the pencil of multi diameters(5mm~14mm);Third, Need in accordance with the user, cut out the multi-form pencil nib. In the text, we will explain how to design the pencil sharpener with the development history of pencil sharpener, and existent patent and commercial product. The design process of this research adopts the following ways:Development design concept 3D computer-aided design, and makes model and test actually. This research designs and makes the prototype of three editions altogether. It has already reached the goal of the preliminary definition in prototype to the third edition. In the text, we will make a description of the design concept of each edition of prototype of pencil sharpener.