Abstract: It is an effective strategy to simultaneously optimize impedance matching and enhance dielectric loss by interface engineering for improving microwave absorption. Here, low-loss interfaces formed by pyrolytic carbon (PyC) are incorporated into carbon nanotube (CNT) hollow microspheres via spray drying. The dielectric properties of the composites can be effectively controlled by adjusting the graphitization degree of PyC through heat treatment temperature (700-900 ºC). As the temperature increases, the absorption performance first enhances and then declines, peaking at 800 ºC due to the optimal balance between polarization and conductivity losses. The PyC-CNT interfaces enhance both impedance matching and electromagnetic attenuation, broadening the bandwidth from 2.5 to 4.0 GHz compared to CNT hollow microspheres. The optimized composite achieves a minimum reflection loss of -45.0 dB at 10.2 GHz and an effective absorption bandwidth of 4.0 GHz at 2.3 mm thickness. This work explores an interface-engineered design strategy for efficient microwave absorbers.