Abstract: The paper presents the potential problem in traditional microwave extractor design in the magnetically insulated line oscillator (MILO). Through high frequency electromagnetic simulation, the dependence of TEM mode transmission efficiency on frequency is obtained at different impedance of the microwave extractor. Simulation results show that the microwave extractor designed in traditional way can not meet the demand of TEM transmission. In order to conquer the transmission difficulty of TEM mode, the paper introduces the scheme using ladder load. Further simulation results indicate that the ladder load conquers the transmission difficulty of TEM mode and improves the adaptability of the microwave extractor to frequency drifting of the MILO.