The characteristics of parallel robot closure mechanism just make up for the deficiency of the serial robot mechanism performance. In recent years, the number of studies and applications of parallel robots have increased rapidly. While, limited workspace is one of the main disadvantages that appear on parallel robots. In this paper, the principle and structure of a Quattro parallel robot are introduced, the kinematic model of a Quattro parallel robot manipulator is established, the workspace is investigated through changing robot parameters, and the most important influence on workspace of the Quattro parallel robot is obtained though calculation and analysis. Also, based on the influence factor, the arm length and the deflection angle of the ball joint are determined to get a desired workspace.