Application of oxygen-enriched combustion technology in oil field steam injection boilers and its preparation method were introduced. According to the known parameters of boiler and fuel properties, amounts of combustion improver and flue gas were calculated for two cases of normal air combustion and oxygen-enriched combustion. Energy-saving efficiency was also calculated in the view of thermal balance. The results show that amounts of combustion improver, flue gas, fuel and the heat loss of flue gas all reduce;The heat loss of flue gas is the main factor to affect the efficiency of energy saving. Thus the measures to improve the efficiency are put forward, which can provide the reference for application of oxygen-enriched combustion technology in future.