In order to recover the heat from low-temperature flue gas in the pusher-type reheating furnace, setting an injection device in the preheating zone was proposed to improve convection heat transfer. Good results have been obtained in the laboratory simulating hot injection. The mean heat flux and total heat transfer coefficient can be increased by 26% and 52-66%, respectively, under the following conditions: temperature in furnace at approximately 750-950 degree C, and temperature of injected gas at 370 degree C.