This paper addresses payload capability performance analysis of a two degreeoffreedom planar parallel manipulator with planar translational motion and small inertia. Unlike the traditional analysis and optimum design method, the geometric parameters and the range of input variables of the manipulator are considered together as the kinematics parameters to obtain the new design space which is different with the traditional one by utilizing the theory of geometric model of the solution space method. The global payload capability indices are calculated in the new design space, the atlases for payload capability of the manipulator are plotted, and the relationship between the kinematics parameters and the indices is discussed. The performance atlases are very convenient for a designer to evaluate the payload performance and select the optimum kinematics parameters of the manipulator, and the new method also provides a useful analysis and design way for the planar parallel manipulators with prismatic actuators.