Three calculation formulas are derived based on the definition of coupling coefficient by three methods, namely, adding electric and magnetic wall method, setting the imaginary part of resistance to zero and S parameter method. The hairpin coupling microstrip resonator module is established and calculation methods is given by using microwave simulation software. The coupling coefficient is calculated and simulation results are obtained under the circumstance of variable interval between resonators. Three calculation results are shown. Firstly, the method of adding electric and magnetic wall is an accurate method in calculating the coupling coefficient between resonators, but it is only suitable for symmetrical structure. Secondly, the method of circuit resistant calculation is an accurate method in engineering, but the calculation of loaded Q is more complicated. Thirdly, S parameter method uses microwave simulation software to obtain the amplitude and phase curve of transformation parameter S 21 , it doesn't has much requirement on the resonator structure, and it is suitable for computer simulation and engineering design.