Abstract: The strut-and-tie model (STM) and reinforcement design method for corner rectangular anchor block of external tendons were studied in this paper. The paper investigated the stress concentration and transferring path of the anchor force through stress distribution analysis, topology optimization, cracking pattern observation, and shear friction mechanism application. It is revealed that the stress concentration can be characterized by four typical local actions and the anchor force is transferred into the slab from the anchor plate through the arch and truss mechanism. Meanwhile, the formula for calculating the allocation of the anchorage force between the box girder web and flange was suggested based on the results of finite element analysis. And two individual refined trussed plane STMS were proposed to account for the properties of tension, compression and shear in corner rectangular anchor blocks. Moreover, the reinforcement design method was given through the combination of the proposed STM and AASHTO LRFD Specification. Finally, a worked design example was presented to demonstrate the effectiveness and convenience of the proposed method.