Calculation of circulating current in transposition bars is the key problem in the design of stator windings, which will determine the transposition type of stator windings. The circuit equation method, in which the calculation of strand end leakage reactance in transposition bars is the premise, is widely used in engineering to calculate circulating current. This paper describes an analytical algorithm for the calculation of strand end leakage reactance in transposition bars, which is based on mirror image principle. The end leakage reactance of strands in transposition bar is calculated by the integral of transposition path discretized into many key points. Contrary to the existing calculation method, the analytical algorithm proposed in this paper is a general method for calculating the end leakage reactance, which can simulate the transposition path of strands in the end region for different transposition types. In order to validate the proposed method, the end coil self and mutual leakage reactance are calculated by proposed analytical algorithm and finite element method.