Abstract: Objective: 30 cases of frameless stereotactic operations were performed with domestic robot CRAS-BH2 (computer and robot assisted surgery, type BH2). Methods: This robot system contended the intellectual machinery arm, image guiding device and 3 dimensional software. Instead of traditional stereotactic frame, the system established the 3D coordinate according to the marks added to patient's head. It showed the target position and the trace of puncture automatically. The intellectual arm could follow the trace and fix the direction, to give doctors the navigation and platform during operation. Results: Thirty frameless operations were successfully performed, which included 23 intratumoral irradiation, 3 biopsy of brain lesion, 2 drawing of abscess and 2 removal of metal body. Conclusion: It could release the patients' pain, convenience the doctors and increase the safety for the robot system to assist the stereotactic frameless operations. There would be a wide application in neurosurgery.