Chemical-looping combustion (CLC) is a novel combustion technique with CO 2 separation. Magnetite (Fe304) was selected as the oxygen carrier and Shenhua coal (Inner Mongolia, China) as the fuel for this study. The influences of operation temperatures, and coal to Fe 304 mass ratios on the reduction characteristics of the oxygen carrier were investigated using an atmosphere TGA. The sample, comprised of 2.25mg coal and 12.75mg Fe304, was heated to 1000 "C. Experimental results show that the reaction between the coal volatile and Fe 304 began at 700°C while the reaction between the coal char and Fe 304 occurred at 800°C and reached a peak at 900°C. Fe304 was fully reduced into FeO, while some FeO was further reduced to Fe. As the operation temperature rises, the reduction conversion rate increases. At the temperatures of 850°C, 900°C, and 950°C, the reduction conversion rates were 37.1 %, 46.5%, and 54.1% respectively. When the mass ratios of coal to Fe 304 were 5/95, 10/90, 15/85, and 20/80, the reduction conversion rates were 29.5%,40.8%,46.5%, and 46.6% respectively. With the increase of coal to Fe304 mass ratio, the conversion rate increases first and then changes no more. There exists an optimal coal to Fe 304 mass ratio.