Abstract: The strut-and-tie model (STM) and reinforcement design method for isolated rectangular anchor block with external tendons were studied in this paper. Firstly, through spatial stress analysis, experimental verification based on crack distribution pattern, topology optimization and mechanism analysis on shear reinforcement, the paper revealed that the stress concentration was caused by three typical local actions and the anchor force was transferred to the slab through the arch and truss mechanisms. On this basis, a new refined trussed STM for isolated rectangular anchor block was proposed, which was capable to reflecting the distribution of tension, compression and shear in anchor block. Moreover, the reinforcement design method was given by the combination of the proposed STM and AASHTO LRFD Specification. Finally, a design example was presented to demonstrate the effectiveness and convenience of the proposed method.