Objective:To investigate the stress distribution on the post of a cast alloy post-core system by three-dimensional finite element analysis. Methods:A three-dimensional finite element analysis was performed. A simulated post/core/crown restoration was constructed on conventional tooth preparations with various diameter of posts and 2.0 mm ferrules. The crown was loaded with a simulated 100 MPa force at 60° angle with tooth longitudinal axis on the palatal surface of the crown. Von Mises stress within the post structure was recorded and analyzed. Results:In the model the Von Mises stress on the top of the post was much larger than that of the tip of the post. Conclusion:The study confirms that the figure of the top of the post should be column,and the diameter of the post in the tip part should be decreased as soon as possible.