Abstract: This paper reports the magnetizing roast of oolitic hematite ore,including the dependency of the magnetization effect upon magnetization temperature,magnetization time,biomass content and ore particle size. It is indicated that the oolitic hematite ore with a particle size of 0.074 mm(>72.5%) is completely magnetized in 30 min by biomass-generated gases and tar at 600℃ when the ore-to-biomass mass ratio is 10:2,which verifies the feasibility of this substitution of biomass for coal as a reductant for magnetizing roast. In addition,the particle size of the oolitic hematite ore has great effect on the reduction index of magnetizing roast. The larger the particle size,the longer the complete magnetization time is. According to the character of biomass,the magnetic properties of the oolitic hematite ore can be effectively improved by appropriately decreasing the particle size.