A novel method to automatically position the standard dental crown for the design of dental crowns is proposed. We use margin feature points to fit a plane, and the path of insertion is just a line perpendicular to the fitting plane, as well as through the centroid of the margin feature points. Besides, we can get the information of the matching points, one on the standard crown model and the other on the neighboring tooth model. According to these, the positioning datum is constructed. Finally through a series of three-dimensional transformation, automatic positioning of the standard dental crown can be implemented rapidly.