Objective：To evaluate the efficacy and safety of the ‘ball tip’ technique in placing thoracic pedicle screw（TPS） as com－pared with the conventional ‘freehand’ technique. Methods：Totally 79 patients scheduled for ＴＰＳ placement from January 2010 to Jan－uary 2011 were divided into group Ⅰ（37 patients，with ball tip technique） and group Ⅱ（42 patients，with conventional free hand tech－nique） randomly. All patients in both groups were scanned by intraoperative 3D-C arm or postoperative CT to measure the accuracy and safety of TPS placement and the pedicle perfo－ration. Results：Totally 478 screws were placed and perforation was occurred in 10 screws（4.45%） in groupⅠand 67 screws（26.48%） in groupⅡ（P <0.001）. In groupⅠand groupⅡ，the respective numbers of TPS with pedicle perforation ≤ 2 mm were 8 and 48（P <0.001），with pedicle perforation between 2-4 mm were 2 and 18（P =0.001） and with pedicle perforation > 4 mm were 0 and 1. One case in group Ⅱsuffered segmental back pain after surgery but recovered by using neurotrophy drugs at one week postoperatively. No vascular，internal organ，neurological injuries caused by TPS placement was occurred in the others patients in both groups. Conclu－sion：The ‘ball tip’ technique shows high accuracy and safety in TPS placement as compared with the conventional ‘freehand’ tech－nique.