Abstract: CyberKnife is a frontier, image-guided and frameless stereotactic technology for radiotherapy of tumors. It can deliver radiation to the target area which can not be reached by techniques of conventional stereotactic radiotherapy. Advanced image-guided system can be used for real-time monitor and tracing of the target area and, automatic correction for position of the treatment couch or direction of the radiation beams can be conducted to compensate the target movement, if the target area was moved. Non-isocentric irradiation allow the dose distribution of radioactive rays to reach the maximal conformality and homogeneity in the lesion to eliminate the cold or hot spots in the target area as appeared in the conventional stereotactic radiosurgery. CyberKnife can be used for single fraction or hypofraction, a true and brand-newstereotactic radiosurgery system for various tumors.