Carbon content of fly ash is one of the important parameters for evaluating the combustion efficiency of coal-fired boilers, so its online measurement is of great significance for improving the energy saving level and intelligent development of coal-fired units. As a competitive on-line measurement technique, laser-induced breakdown spectroscopy (LIBS) has made great progress in fly ash carbon content measurement. The progress of basic research on LIBS measurement of carbon content in coal combustion fly ash is summarized. According to the differences in the morphology of fly ash samples during measurement, the optimization methods of LIBS measurement parameters in different measurement modes are sorted out firstly. Then, the current development trends of spectral data processing methods and quantitative analysis algorithms for LIBS measurement of fly ash carbon content are summarized. Finally, the current application of LIBS for fly ash carbon content measurement in real industry is reviewed, and the future research direction is prospected.