To increase the accuracy and efficiency of Total Knee Replacement (TKR) surgery, surgical robotic systems are introduced and accepted in the surgical community. However, present surgical robotic systems unfortunately occupy a significant amount of space in operating room and prohibit flexible movement between the patient’s femur and robot. In this paper, a small occupancy assistant for TKR surgery is developed, which consists of three components: articulated manipulator, bone clamp, and mechanical support arm. The detailed design of the three components is presented. The performance of prototype shows that the compact mechanisms solve the above problem absolutely and lead convenience to surgeons. The study provides a significant approach for the following research in TKR surgery.