According to the mechanical and structural characters of externally prestressed box girder with corrugated webs,the mechanical performance,such as load bearing mechanism,mechanical characters,damage form and ultimate load capacity of concrete rib deviator used in externally prestressed box girder with corrugated webs is studied using FEA(Finite Element Analysis) and experimental methods.The experimental and FEA results fit each other well.The research indicates that the local influence in concrete flange caused by deviator concentrates in the joints of deviator and concrete flange and the nearby location.When the deviator damages,the tensional concrete cracks and the round reinforcements yield and compressional concrete splits.The compressional concrete shows obvious characteristics of eccentric compression member.The conclusion of this paper may be helpful for designers in designing deviators of externally prestressed box girder with corrugated webs.