The stress distributions of acromio-clavicular joint (AC joint) complex for human shoulder in intact condition, injured condition and two reconstruction procedures were presented in this paper. Two-dimensional finite element (FE) analysis was used to investigate various situations of AC joint from engineering viewpoint. The models are validated through comparison with the experimental results of Debski et al.17 The results showed that the stress shifted to trapezoid ligament and conoid ligament once the AC joint was injured. The modified Weaver–Dunn procedure is better than the Neviaser procedure since the graft alleviates more stresses from trapezoid and conoid ligaments. The coraco-acromion ligament (CAL) plays an important role in the AC joint complex. AC joint complex model can provide alternative evidence to elucidate the detailed anatomy and functional role of each AC joint structures and numerical evidence for the advantage of specific procedures of AC joint and may serve as a potential tool to screen out improper material implementations and surgical procedures in the future.