Chemical looping combustion (CLC) is a promising technology to capture CO2. However, the low conversion efficiency of fuel is the key challenge for the in situ gasification CLC with natural iron ore as an oxygen carrier. The reactivity of the selected 696 K2CO3-modified iron ore (6KMIO) was first determined by H-2 and CO in TGA, and an enhanced reduction reactivity of 6KMIO was confirmed. Afterward, the feasibility of 6MKIO for coal CLC was tested in a 1 kW continuous reactor. The continuous reactor could be stably operated without any tendency of agglomeration or sintering among 6KMIO particles. Compared with use of the raw iron ore, the use of 6KMIO enhanced the coal conversion and the gasification-products conversion, promoting the CO2 capture efficiency. Furthermore, the mechanism of the catalyzed coal CLC process and the release of sulfur was explored.