The combustion characteristics of mixture of antharcite and bituminous coal were studied in a fluidized bed(0.155m-I.D., 2.2m-height). The pressure fluctuations were measured by a pressure transducer under the various operating conditions. The properties of the pressure fluctuatuons, such as the standard deviation of pressure fluctuations, static pressure, cross-correlation function, dominant frequency and the power spectral density function, were obtained from the statistical analysis. The pressure fluctuation properties, particle size distribution of ash and composition of flue gas were measured to interpret the combustion characteristics in a fluidized bed combustor uniform of multi-sized particles of mixed anthracite and bituminous coal have been compared with the particle size distribution, antharcite mixing fraction. From this study, the combustion characteristics of mixed fuels in a fluidized bed combustor coulde be intetpreted by using standard deviation of pressure fluctuation and power spectrum distribution.