Pressure fluctuations are often selected to analyze the dynamic changes in the fluidized bed. Many researchers in the field of fluidization have adopted many methods to analyze the pressure signals in fluidized beds, such as statistical analysis (in time domain), frequency analysis (in frequency domain) and nonlinear analysis (such as chaotic method). There are many literatures concentrated on statistical analysis in the fluidization field since this method can display the distribution density of the pressure fluctuations. In this study, the pressure fluctuations on the bed wall at different bed heights in the cold two dimensional (2-D) circulating fluidized bed (200 x 30 x 1200 mm(3)) were sampled. The colophony, millet and 20% millet plus 80% colophony were selected as bed materials. The pressure signals were analyzed by means of statistical methods. The correlation equations between the pressure signals and fluidization parameters were obtained under different operational conditions. Finally, comparisons between the single solid and binary solids 2-D circulating fluidized beds were investigated deeply. Two parameters, K-1 (=0.54(u - u(mf))(0.4) h(0.8)/g(0.2)) and K-2 (=sigma(b)/(rho(s)g(1 - epsilon(mf)))), were selected to characterize the fluidization mechanism. It was found that the relationships between K-2 and K-1 among the single solid and binary solids circulating fluidized beds vary a great deal. (c) 2005 Elsevier Ltd. All rights reserved.