This experiment was performed on characteristics of exhaust gas(CO) of CFB boiler and monitoring of poor fluidization of FBAC. As the addition amount of the bituminous coal into the anthracite was increased, the reactivity of the anthracite was found to be improved. Unburned carbon in fly ash was decreased with increasing the ratio of bituminous coal in co-combustion. By experiments, the optimum conditions of co-combustion ratio was under 50%. The increase of linear air flow rates from exhaust to entrance of the FBAC was the most effective. By collecting the signal of the pressure change, we can confirm that occurrence of the defluidization area could be found. After this, if these technology is applied in practical power plant it will make for achievement of stable operation and mitigation of economical loss.