Objective To study the method and outcome for intercondylar comminuted fractures of the humerus through open reduction and internal fixation with AO reconstructive plate. Methods From March 1997 to September 2000, 31 cases of intercondylar comminuted fracture of humerus were reviewed, which involved 24 males and 7 females with an average age of 37.4 years (range, 18-67 years). The fracture was located on left side in 17 and on right side in 14. According to AO/ASIF classification, there were C1 in 11, C2 in 12, and C3 in 8, among them, 9 cases were open fractures including of Cusstilo and Aderson typeⅠin 5 and Ⅱ in 4. Posterior trans-olecranon osteotomy with open reduction and internal fixation by AO reconstructive plate or plus 1/3 tube plate were performed in all the cases within 48 hours after injury. The osteotomy was "V" shape at 2 cm to proximal end of ulna. All the patients began the passive motion exercise within 24-48 h, and active training at one week postoperatively. X-ray was taken in 1, 3, 6 and 12 months after operation to observe the bony union. 5 cases with ulnar nerve injury underwent nerve exploration and anterior transposition. Results All the cases were followed up 1-3.4 years (average, 1.5 years), the fractures healed well, and the elbow function recovered satisfactorily. According to the Cassebaum scoring system, 11 were assessed as excellent 11, good 14 and fair 6, and the excellent-good rate was 80.6%. The complications included 1 infection, 1 heterotopic ossification and 2 injuries of the radial nerve, which recovered with dressings, antibiotics and neural nutrients. Conclusion The technique of AO reconstruction plating for the intercondylar comminuted fractures of the humerus through trans-olecranon approach offers many advantages, such as sufficient exposure, anatomical reduction, stable fixation, earlier exercise and satisfactory elbow function.