The seal prevents leakage by the rib and the rotating shaft are in contact due to the fluid operating pressure. Recently, studies are focused on making the lubricated surface of thrust bearings, mechanical bearing, and piston rings shaped a micro dimple or micro pocket to reduce the friction force of the smooth surface and increase part life. This paper analyzed various kinds of dimple shapes on the seal surface, i.e. circle, rectangle, triangle, and trapezoid. For this purpose, the design of experiments are introduced to work out a dimple configuration, unlikely to be damaged from cracks and low in contact stress. The triangular type dimple marked the best results. The factors for the best dimple were 0.15 mm in size, 0.0383 mm in depth, and 40% in density while the maximum equivalent stress was 9.1455 MPa and the maximum contact pressure was 9.6612 MPa.