Plates are One of the most useful parts and pieces of industrial systems and structures which are under load so that most important and extended usage of them is producing structures for example airplanes, aircrafts, sea structures in mechanical and structural engineering. One of the important point in designing such structures which are under dynamic loads is forbidding resonance. So for designing in thi parts, increase the natural frequency has beeoffered. In this thesis try to achieve optimum distribution of mass and stiffness for achieving maximum amount for natural frequency with use optimization science in designing optimum thickness of elliptical plate which in that’s vibration analysis, we need to solve an eignvalue problem. Because of complicated geometry and boundary conditions for an elliptical plate, solution of this problem has some difficulty. To achieving optimum thickness topology for elliptical plate, generate mesh and assume that thickness is design variable. So that fundamental natural frequency as a objective function will be maximized. Two types of constraints are in this problem: 1) some of the masses for all of the elements are constant. 2) thickness of every elements has a constraint on their thickness. Solution of this problem has been solved in two steps. In first step, we solve natural vibration problem for elliptical plate with constant and variable thickness under different boundary conditions. In this step we use two way for solve the problem: Reyleigh-Ritz Method and standard finite element. In analysis of second step, results of last step has been optimized and at last with use one of the optimization numerical methods, optimum distribution of mass and stiffness for achieving maximum fundamental natural frequency under different boundary conditions. In this step, for sensitivity analysis, calculate sense of natural frequency according to design variables. So that optimum topology of elliptical plate with different radius ratio under Free, Simple, Clamp, Clamp-Simple, Clamp-Free and Free-Simple boundary conditions. To maximize the fundamental natural frequency with accurate to constraints and effect of different arguments to optimum topology. Key Words Optimization, Reyleigh-Ritz, finite element, natural frequency, elliptical plate.