The　effects　of　actuator　disposition　and　redundant　actuation　on　performance　of　the　3-DOF　Tricept　parallel　mechanism　are　analyzed.　For　eighteen　redundant　and　non-redundant　actuating　modes,　the　corresponding　Jacobian　and　stiffness　matrices　are　educed.　According　to　the　distributing　properties　of　the　kinematic　dexterity,　the　maximal　and　minimal　stiffness　indices　on　mid　section　of　mechanism＇s　positional　workspace,　the　performance　characteristics　of　tricept　mechanisms　with　different　actuator　disposition　and　redundant　actuation　are　contrastively　investigated.　As　a　result,　the　actuating　modes　which　can　simultaneity　enhance　the　kinematic　dexterity　and　stiffness　characteristics　are　presented.　The　investigation　shows　that　redundant　actuation　has　less　effect　on　dexterity　and　stiffness　of　the　tricept　parallel　mechanism　in　which　the　sliders　of　UPS　sub-chains　are　adopted　as　the　driving　joints,　but　it　can　evidently　improve　kinematic　dexterity　and　stiffness　characteristics　of　the　mechanisms　with　actuating　rotational　joints.　Thus,　the　redundant　actuators　can　be　added　to　the　Tricept　mechanism,　in　which　the　rotational　joints　of　UPS　sub-chains　are　used　as　the　driving　joints,　to　acquire　better　mechanism　performance.