We highlight the joint torque optimization problem of redundant manipulators and introduce a new concept, dynamic dexterity, for controller design. Similar to the kinematic dexterity, the measure for the robotic mechanism design, dynamic dexterity, can serve as an important criteria for the design of redundant manipulator controller. Clearly, kinematic dexterity is intrinsic to a robotic mechanism, it can also be used as a measure of controller design for redundant manipulator. However, the only geometric relation with robotic mechanism limits its capacity to serve as a criterion for controller design. Some other fateful factors should be considered simultaneously in controller design, and they are included in the new dynamic dexterity criteria. Theoretical analysis and simulation have shown that dynamic dexterity is very useful for the controller design.