<p>A novel robotic system for long bone fracture reduction is developed to address the drawbacks of reduction surgery in clinical practice such as infection, non-union, and malunion. Compared to existing robotic systems, the proposed robotic system integrates a novel semi-automatic surgical planning method and can perform the reduction automatically under supervision, thereby assisting surgeons throughout the whole clinical process. Besides, the proposed robotic system utilizes both optical tracking data and robot kinematics to calculate the position of fragments during the execution of fracture reduction, thereby increasing tolerance to line-of-sight interruption. Radiation exposure to surgeons is minimized since C-arm devices are not required. Trajectory planning experiments using clinical data from tibial, femoral, and fibular fractures are conducted to validate the surgical planning method, in which the generated path length is shorter than that achieved by existing methods. Phantom experiments are performed to evaluate the system’s accuracy, where the mean translational error is reduced to 0.96 mm and the rotational error about the <i>z</i>-axis is 0.26°, both meeting clinical requirements, indicating that the proposed system has the potential to assist surgeons with more precise operations, thereby achieving higher reduction accuracy and minimizing the reduction path length for patients.</p>