A 2-DOF planar parallel robot including parallelogram linkages is introduced in this paper. A set of closed form parametric relationships of links length is founded based on kinematic model and optimal configuration analysis. Aimed to achieve good dexterity, high accuracy and high speed, an optimal kinematic design method of 2-DOF planar parallel robot is proposed to optimize the length of links. Dexterity and isotropic configuration are analyzed, which are used in workspace synthesizing. The proposed method can be implemented in two steps. In the first step, under the constraints of dexterity, minimum transmission angle, a workspace with desired kinematic performance is achieved, and a set of possible optimal results is generated by objective workspace searching. In the second step, a global index, which is composed of conditioning index of Jacobian matrix, velocity and motion resolution, is used to filter the most optimal solution from the results of the first step, A design example is given to demonstrate the effectiveness of proposed method.