Objective To review the biomechanics of internal fixators for proximal humeral fractures, and to compare the mechanical stabil ity of various internal fixators. Methods The l iterature concerning the biomechanics of internal fixators for proximal humeral fractures was extensively analyzed. Results The most important things for best shoulder functional results are optimal anatomical reduction and stable fixation. At present, there are a lot of methods to treat proximal humeral fractures. Locking-plate exhibites significant mechanical stabil ity and has many advantages over other internal fixators by biomechanical comparison. Conclusion Locking-plate has better fixation stabil ity than other internal fixators and is the first choice to treat proximal humeral fractures.