Abstract: The fine reduction technology for the heat treatmentofiron powder at 800 1000℃ in hydrogen and aSSociated ammonia gas has become an effective means to produce high smndard iron pewder presently.The paPer has given thermodynamics analysis for decarbonlzatlon,deoxldatlon,desulphunzatlon and denitrification,and outlined the key points to be controlled,such as starting iron powder,atffiosphere,temperature,holding time etc.in the process of secondary reducnon.