Current 3D model based line rendering methods produce drawings with a large number of small lines is due to the grid structure of the underlying model, resulting in many obvious corners and isolated segments in the drawings. In this paper, we propose a new sketch style 3-dimensional model line rendering method that transforms an observed 3D model into a drawing with simple and natural lines. Firstly, the method uses Suggestive Contours to get characteristic lines of the model. Then, these small lines are connected into a few long lines by analyzing their spatial information. Finally, cubic B-spline curves are utilized to interpolate the resultant lines with some simplification processing using B-spline wavelets. The rendering results show that the proposed method can connect characteristic lines well and get smooth and simple sketch style drawings.