Synthetic coal char (SCC) was made from nanocarbon powder, sucrose, deionized water, and ethanol in appropriate proportions and then pyrolyzed at 800 or 900 degrees C. SCC samples modified by different microwave power were investigated for reduction of NO in a microwave-electrothermal reactor system. The results showed that with increasing microwave power, the reactivity of SCC with NO first increased and then decreased. The optimum microwave power was 640 W for SCC pyrolyzed at 800 degrees C for 20 min (800 degrees C SCC) and 480 W for SCC pyrolyzed at 900 degrees C for 20 min (900 degrees C SCC). In addition, the higher the pretreatment temperature, the better the effect of microwave modification. To investigate the mechanism of modification of SCC by microwaves, mercury intrusion analysis, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy were performed on 800 degrees C SCC samples. The changes in the pore structure, graphitization degree, and oxygen functional groups were determined. With increasing microwave power, the specific surface area and pore volume of SCC first increased and then decreased, while the degree of graphitization showed the opposite trend. After microwave treatment, the relative contents of C-O, C-O, and O-C-O decreased.