||Coal gasification fine ash (CGFA) having a high carbon content is produced in large quantity as a byproduct from coal gasifiers in China. CGFA is usually disposed of by landfill as a solid waste, which is not only detrimental to environment but also a loss of an enormous energy that renders the process inefficient. Therefore, it is crucial to make use of the high carbon content in the CGFA with an economic and environmentally friendly method. In this study, the ignition and burnout behavior of CGFA were investigated via a thermogravimetric analyzer (TGA), flat-flame burner (FFB), and drop-tube furnace (DTF). Further, the cofiring of CGFA was numerically studied in a tangentially fired pulverized coal boiler burning anthracite with various cofiring ratios (0%, 10%, 20%, and 30%). The TGA results show the similar oxidation reactivity, oxidation kinetics, and ignition behavior of CGFA with the anthracite. In the FFB atmosphere with practical heating rates, the CGFA and anthracite are both heterogeneously ignited with an ignition time of 8.1 and 7.6 ms, respectively. The particle size significantly affected the ignition time of CGFA, as the particle size decreased from 125 to 135 μm to 45–63 μm and the ignition time of CGFA decreased from 10.1 to 5.6 ms. The burnout test in DTF indicates that the promising burnout performance in a pulverized coal furnace required a crucial oxygen concentration >10%, and the CFD simulation results coincided well with the experimental data from DTF. The CFD modeling results of the full-scale furnace show that the cofiring of CGFA is feasible in the pulverized coal furnace burning anthracite. Compared with the mode of pure anthracite combustion, under the cofiring mode with 10–30% CGFA as the energy input, the central maximum temperature of the main combustion zone increases by 50–90 °C, resulting in the slightly improved burnout for both anthracite and CGFA.