Abstract: It is necessary to obtain permittivity and permeability of microwave-absorbing material FeSiAl. Based upon transmissionreflection method, the complex electromagnetic parameters of FeSiAl were measured by dint of VNA (vector network analyzer). The simulations were done with CST Microwave Studio. Experiments and simulations both indicate that the gap between samples and the test fixture influences the parameter results seriously. Consequently several mixed samples of powdered FeSiAl and paraffin were made with different mixing percentages. They maintained stable electromagnetic characteristics in a broad microwave band. The electromagnetic parameters of FeSiAl were extracted from the mixture’s electromagnetic parameters based upon optimal equivalent formulas accurately．