Abstract: The direct kinematics for parallel robot is important and difficult problem. In this paper the direct kinematics for a class of 6-SPS parallel manipulator is studied by symbolic computation approach and Dialytic elimination method. Lead to a polynomial equation in one variable, the analytic solutions of the direct kinematics are derived. Then the workspace determined, the all real solutions are given. The method is suitable to the direct kinematics of a general 6-SPS, parallel manipulator.