Objective: To retrospectively analyse clinical features and related factors of brachial plexus palsy associated with halo traction before posterior correction in severe scoliosis. Method: 300 cases of severe scoliosis performed with halo traction before posterior correction wereconsidered with 7 cases suffering from brachial plexus palsy (2 males and 5 females). The average age was 14 years (range, 9–19 years).The average Cobb angle was 110° (range, 90° – 135°); Diagnoses were idiopathic scoliosis (1), congenital scoliosis (3), and neuromuscular scoliosis (3). Halo-gravity traction was used in 3 cases preoperatively; and Halo-femoral traction used in 4 cases postoperatively (anterior release 2 cases, anterior epiphyseal arrest 1 case, combined anterior and posterior release 1 case). Results: Traction was used for an average of 3.5 weeks before spinal fusion (range, 2–6 weeks) for these 7 patients. The average traction weight was 8kg; the average traction weight was 19 % ( range 13–26%) of the average body weight (40.2kg). The mean stature was 175cm; all the 7 patients had a long and thin body configuration. Duration between brachial plexus paralysis and detection was 1 to 3 hours. All the 7 patients suffered different degree from numbness of ulnaris of the hand and antebrachium. Median nerve palsy was found in 3 cases, ulnar nerve paralysis was found in 4 cases. Complete nerve functional restoration had been achieved by the end of three months after rehabilitation training, drug treatment were adopted. Conclusion: Brachial plexus palsy associated with halo traction in severe scoliosis is related to the weight of traction, body type and patient-pathology status. If the symptoms are promptly detected with rehabilitation training and appropriate drug treatment adopted, complete nerve functional restoration can be achieved.