The surface modification was used on FSC（FeSi₇Cr₃）magnetic powder with the coupling agent KH560 through the ball milling process.The microstructure and thermal analysis properties of the surface modification layer were analyzed by scanning electron microscopy（SEM）and thermogravimetric analysis（TG）.The vector network analyzer was adopted to measure the electromagnetic parameters of the microwave absorbing materials.The results show that the shape of the magnetic powder particle is changed from spherical to flat after ball milling treatment.TG results show that the sample after surface treatment still has good oxidation resistance after oxidation for 4 hat 900℃.The electromagnetic parameter results show that the dielectric parameters of the sample after high temperature oxidation are decreased,which is conducive to improving the dielectric matching of microwave absorbing materials.The high-temperature oxidation results show that the surface modification of FSC magnetic powder with coupling agent KH560 can improve the high-temperature resistance of the microwave absorbing material.The surface-modified FSC magnetic powder still maintain good microwave absorbing properties after high temperature treatment.At the oxidation temperature of 700～900℃,the reflection loss peak is shifted from 4 GHz to high frequency near 6 GHz,and the reflection loss performance is kept at approximately 15 dB.The surface-modified absorbing material shows the satisfied oxidation resistance and microwave absorbing characteristics.