In this paper, we propose a method that can beautify user's handwriting to the character of Kai style calligraphy. Structural and style features of Chinese character are summarized, and a model for representing character is proposed. Bezier curve with varying width is used for approximating user-input stroke segment. Corner shapes are modeled and utilized to beautify the corner points in the stroke. Rendering rules are designed based on the character features. Also, antialiasing technology is adopted to make the edge of the contour fine and smooth. Experimental results show the effectiveness of our system on beautifying the handwriting to Kai style calligraphy.