To obtain the high-efficiency electromagnetic (EM) wave absorber, two-dimensional layered Ti3C2Tx/Co spheres/TiO2 nanocomposite powders were prepared by heat treatment, and the samples were characterized and analyzed by SEM, XRD and XPS. The electromagnetic parameters of the samples were tested by vector network analyzer and the reflection loss values (RL) of the samples were simulated and calculated at different coating thicknesses. The results showed that the mass content of TiO2 in the samples increased with the increase of heat treatment temperature; when the heat treatment temperature is 400 ℃, the RL of the sample reaches -45.7 dB at 7 GHz with a coating thickness of 3 mm, and the effective absorption bandwidth is as high as 10 GHz (3 ~ 5 GHz, 10 ~ 18 GHz) at 4 mm. Finally, electromagnetic wave absorption mechanism of Ti3C2Tx/Co spheres/TiO2 nanocomposites was analyzed. It was proved that Ti3C2Tx/Co sphere/TiO2 nanocomposite is a very promising electromagnetic wave absorbing material.