Abstract: Taking GW5000-Y/6.4-Y2 type of direct heater and 4 650 kW hot medium heater as an example, a technical and economical comparison for direct heater and indirect heater was made, and concluded that direct heater is simple in structure, hot medium heater is superior to direct heater from the point of safety, corrosion of furnace tubes, scaling, coking and pressure bearing, direct heater is cheaper than hot medium heater based on the investment of equipment, the cost of running, maintenance, hot medium heater can conbine "two sets of flame" into "one set of flame", but direct heater is impossible, direct heater is lower in low temperature corrosion.