A surface tracking-based surgical robot system for drilling operations includes surface scanning equipment, a robot arm, and a workstation. To perform a drilling operation, surface information for the target surgery area and the surgical tool held by the robot arm is simultaneously collected with the same surface scanning equipment. A preoperative 3D image of a surgical area and a CAD model of the surgical tool are registered to the collected surface information, through which the relative position between a surgical path and the surgical tool is obtained. Using this relative position, the robot arm aligns to the predefined surgical path using a feedback control method running on a workstation. The drilling operation is then autonomously executed by the robot arm or manually performed under the guidance of the surgical tool held by the robot arm.