The numerical simulation in the combustion space of a float glass furnace was carried out. Under the premise of ensuring the same fuel calorific value, the flow field distribution characteristic of heavy oil combustion and co-combustion of petroleum coke and heavy oil was studied. The results showed that the two fuels can co-fire well, and the temperature system in the furnace was basically unaffected. In contrast, the petroleum coke's ignition time was longer than that of the heavy oil, so the average ignition point of the fuel during co-combustion lags behind when only heavy oil was used and the flame was longer. When the fuel was co-firing, more O2 was needed, the combustion was not enough, and a large amount of CO was generated. Finally, the total NOx emission at the flue gas outlet was reduced by 30.02% compared with the case using heavy oil only, and the NOx emission reduction effect was obvious.