With chemical analysis and micro analysis methods, the paper investigated the distribution of free lime in CFBC fly ash, and the ways (heat treatment and preliminary humidification) for elimination of free lime to improve the utilization of CFBC fly ash in cement and concrete. The research results showed that more than 80% of free lime appeared below the particle size 75μm of CFBC fly ash in this test. Besides, preliminary humidification was proved to be more beneficial for eliminating free lime in CFBC fly ash, and the content of free lime reduced to 1.0% with the humidification time of 7 days.