Abstract: To study the problem that there is a horizontal sidesway between transfer and receiver coils in magnetic resonance coupling wireless power transfer,the mutual inductance coupling theory and twoport network theory is adopting for modeling analysis.The expression of normalized transmission power and transmission efficiency expressed by s parameter by mathematical derivation.The HFSS software is utilized to simulate the impact of the horizontal sidesway on system’s transmission performance under the condition of overcoupling,critical coupling and undercoupling.An optimal structure for improving the system is presented.In the end,the reliability of simulation results is verified by experiment,and the experiment proves that the optimized structure should eliminate the negative effect brought by the sidesway effectively ,and improve the transmission efficiency of the system.