Using Geldart's A-particle, the local variables of bubble properties including bubble frequency, fraction, size, riding velocity and visible bubble flow rate were measured in fine particle fluidized beds and theoretically discussed. Basing on the experimental results, a model vas newly proposed for estimating the cross sectional-averaged values of bubble variables and the validity of the model were examined. The following were obtained. (1) The radial distributions of local bubble frequency and fraction are parabolic. (2) The radial distributions of local bubble chord length and rising velocity are almost flat. (3) The cross sectional-averaged values of visible bubble flow rate are about 70% of superficial gas velocity. (4) The observed cross sectional values of bubble variables agree well with the values calculated using, the model proposed in this work In addition, the model is also capable for estimating the size of bubbles in fluidized beds where the splitting of bubbles is not observed or can be neglected.