Objective To investigate the correlation between shoulder bony structure and rotator cuff tears by using multi-slice spiral CT (MSCT) technique. Methods A total of 50 patients with unilateral rotator cuff tears and 100 normal adults were selected as study subjects. And 64-slice spiral CT was used to scan the shoulder joints of all the subjects. The indicators of shoulder bony structure were measured and analyzed. The left and right parameters were compared within and between groups. Results There were no significant differences between the right and left sides of the normal subjects (P>0.05). The elevation angle of the affected humeral head nodules in patients was significantly larger than that of the uninjured side and that in normal group (P<0.05). The upward inclination angle and torsion angle of affected scapular glenoid were significantly larger than those of the contralateral side and those in normal group (P<0.05). The distance from the top of the head to the shoulder of patients was shorter than that of the uninjured side and that of the normal group (P<0.05). Conclusion MSCT is simple and reproducible for measurement of shoulder bony structure. The elevation angle of humeral head nodules, torsion angle of scapular glenoid, inclination angle and the distance from the top of the head to the shoulder are related to rotator cuff tears.