With the rapid development of stealth technology, the microwave absorbing properties of composite materials are increasingly required. In this paper, SiC_f /SiC 2D woven fabric was prepared by precursor impregnation and pyrolysis (PIP). The absorbing properties of SiC_f /SiC 2D woven fabric, such as reflection loss, absorbing mechanism and influencing factors, were studied by means of experimental test and numerical simulation. The results show that the SiC_f /SiC 2D woven laminates prepared in this paper have an effective absorption bandwidth of 3 GHz and a maximum reflection loss of –19.2 dB at the absorption peak of 9.7 GHz in the frequency range of 4–18 GHz. Its microwave absorbing performance is closely related to the electromagnetic parameters of the fiber, the microstructural parameters and the incidence Angle of the electromagnetic wave. In addition, it is found that the absorption properties of the composites are mainly due to the special braided structure and the interaction between the fibers and the matrix. These interactions cause electromagnetic waves to be reflected, scattered and absorbed several times inside the material, thus achieving efficient electromagnetic wave attenuation. This paper not only helps to promote the application of SiC_f /SiC composites in stealth technology, electromagnetic shielding and other fields, but also provides a useful reference for the research of other highperformance composites.