In order to make an in-depth study on high-frequency characteristics of GMI effect, this article presents a practical method to generate the alternating magnetic field. Comparing three feasible ways, the microstrip line is the optimum selection. Based on equivalent analysis method and CST software simulation, the distributing of microstrip line magnetic field is analyzed separately. Comparing the results based on different method, simulation results validate that equivalent analysis method is correct. It also indicate that the thickness of substrate and breadth of conductor strip both influence the distributing of magnetic field seriously. In the end, it is suggested that high-frequency alternating magnetic field generated by microstrip line is feasible, and it provides a theoretic reference for the design of mocrostrip line.