Object: To investigate the effect of medial collateral ligament repair and coronal process fracture fixation on the stability of the “Terrible Triad”. Methods: CT and MRI scans of elbow joints were performed from one healthy 28-year-old male volunteer. Make three elbow models: Model A: normal model. Model B: repair of coronal process fractures without repair of medial collateral ligament. Model C: repair of the medial collateral ligament without repair of the coronal process fracture block. Longitudinal loads were applied to analyze the displacement and stress distribution of the elbow joint. It would be compared of the stability of three models with various working conditions. Results: The nephograms of displacement distribution and stress distribution of the three models were similar. The maximum displacement and maximum stress of the articular surface were located at the ulna pulley notch, the minimum displacement was located at the coronal process and it’s medial side. The minimum stress was located at the lower lateral side of the coronal process. There was no statistical difference in the maximum displacement and stress among the models (P>0.05). Conclusion: The lateral structure is very important in the stability of the “horrible triad”. When the lateral column is stable, it is similar in the effect of repairing the medial collateral ligament and fixing the fracture block of ulna coronal process. This also indicates that when repairing the coronoid process of ulna is difficult or imprecise, repairing the medial collateral ligament can replace repairing the coronoid process of ulna.