In order to analyze the seal performance and working station of Oring at delta area, the models of Oring and relevant parts were established with the software ANSYS Workbench. The Von Mises stress, the contact stress and the preload force of the Oring models were analyzed based on different chamfer dimensions. The results show that the Von Mises stress, the contact stress and the preload force are different with different chamfer dimension. The engineer can design the chamfer of the delta area according to different seal pressure requires. The seal pressure and the preload force can be checked at the same time.