Objective To discuss the effectiveness of anterolateral decompression and three column reconstruction through posterior approach for the treatment of unstable thoracolumbar fracture. Methods Between March 2009 and October 2011, 39 patients with unstable burst thoracolumbar fracture were treated. Of them, there were 32 males and 7 females, with an average age of 43.8 years (range, 25-68 years). The injury causes included falling from height in 17 cases, bruise in 10 cases, traffic accident in 4 cases, and other in 8 cases. The fracture was located at the T10 level in 1 case, T11 in 9 cases, T12 in 6 cases, L1 in 14 cases, L2 in 7 cases, L3 in 1 case, and L4 in 1 case. According to Frankel classification before operation, 5 cases were classified as grade A, 5 as grade B, 9 as grade C, 14 as grade D, and 6 as grade E. Before operation, the vertebral kyphosis Cobb angle was (26.7 ± 7.1)°; vertebral height loss was 37.5% ± 9.5%; and the space occupying of vertebral canal was 73.7% ± 11.3%. The time between injury and operation was 1-4 days (mean, 2.5 days). All patients underwent anterolateral decompression of spinal canal by posterior approach and three column reconstruction. After operation, the vertebral height restoration, correction of kyphosis, decompression of the spinal canal, and the recovery of nerve function were evaluated. Results Increase of paraplegic level, urinary infection, and pressure sore occurred in 1 case, 1 case, and 2 cases, respectively; no incision infection or neurological complications was observed in the other cases, primary healing of incision was obtained. The patients were followed up 12-36 months (mean, 27 months). The patients had no aggravation of pain of low back after operation; no loosening and breaking of screws and rods occurred; no titanium alloys electrolysis and titanium cage subsidence or breakage was observed. The imaging examination showed that complete decompression of the spinal canal, satisfactory restoration of the vertebral height, and good physiological curvature of spine at 2 years after operation. At last follow-up, 1 case was classified as Frankel grade A, 2 as grade B, 2 as grade C, 10 as grade D, and 24 as grade E, which was significantly improved when compared with preoperative one (Plt; 0.05). At immediate after operation and last follow-up, the Cobb angle was (6.3 ± 2.1)° and (6.5 ± 2.4)° respectively; the vertebral height loss was 7.9% ± 2.7% and 8.2% ± 3.0% respectively; and the indexes were significantly improved when compared with preoperative ones (P lt; 0.05). Conclusion The technique of anterolateral decompression and three column reconstruction through posterior approach is one perfect approach to treat unstable thoracolumbar fracture because of complete spinal cord canal decompression, three column reconstruction, and immediate recovery of the spinal stability after operation.