This work presents a simple and yet powerful approach for quantitative and qualitative evaluation of the performance of 3-UPU spatial parallel robot. The quaternion approach is used to obtain graphically the workspace of the 3-UPU parallel manipulator. The Jacobian matrix is developed then used to search for conditions that lead to singular configurations where the mobility of the manipulator instantly changes. The condition number of this matrix characterizes the dexterity of a robot manipulator at a given posture in the workplace, which is an important index to measure the performance of the mechanism.The aim of this work is to evaluate all behaviors of the proposed model of spatial mechanism and analyze the kinematic performances indexes, which allows the evaluation and the comparison of the workspace reached by the spherical parallel manipulator, with the workspace required or prescribed for a desired application.