Abstract: The optimization of thickness and embedding position of a piezoelectric actuator in composite laminates is studied. First, a high order coupled model for piezoelectric laminates is presented. Then, a general laminate with a piezoelectric layer is selected as a typical representation, which has no constrains and can deform freely when an electric field is applied through the thickness of the piezoelectric layer. With that assumption that the internal forces on the cross sections of any plate element are zero, a constrained optimization problem is formulated by maximizing the bending or twisting curvature of the laminate. Finally, an isotropic plate with isotropic actuator and a composite plate with anisotropic actuator are analyzed. The three dimensional(3D)curved surface and contour graphs of the object function are given to visualize the results, which show that the effectiveness of the piezoelectric actuator is sensibly relative to its thickness and embedding position, and the optimal thicknenss and position are determined by the material properties of the actuator and the laminate.