Objective To investigate the effectiveness of minimally invasive plate fixation in treatment of unstable pelvic fractures. Methods Between May 2006 and December 2009, 21 patients with unstable pelvic fractures were treated. There were 13 males and 8 females with an average age of 39 years (range, 21-66 years). The causes of injury included traffic accident in 9 cases, falling from height in 6 cases, and heavy pound injury in 6 cases. The time from injury to hospitalization was 1 to 4 hours with an average of 2.8 hours. According to Tile’s classification, there were 12 cases of type B and 9 cases of type C. After admission, bone traction and exo fixation were performed, and minimally invasive plate fixation was given at 5-24 days after injury. Results All incisions healed by first intention, and no complications of nerve and vessel injuries occurred. According to the reduction criteria of Matta radiography, anatomic reduction was achieved in 16 cases, satisfactory reduction in 4 cases, and fair reduction in 1 case. All patients were followed up 12 months. The X-ray films showed all fractures healed at 2-4 months (mean, 2.6 months). According to Majeed clinical evaluation, the results were excellent in 12 cases, good in 7 cases, and fair in 2 cases. Conclusion Minimally invasive plate fixation can provide effective fixation, reconstruct pelvic ring, and reduce perioperative complications in the treatment of unstable pelvic fractures.