Abstract: In order to show the clamping ability of the 6-DOF manipulator fingertip of minimally invasive surgical robot at the clamping point,the fingertip posture,the object gesture and the relations between them during clamping are analyzed. The analytic expression of the fingertip gesture is deduced when the fingertips clamp the object with random postures at a gripping point,and the clamping dexterity is defined with the pose sphere.Clamping dexterity of those discrete points in the workspace of the mechanism is studied,the clamping dexterity space of the fingertips is determined,and is verified by the simulation with SimMechanics.