Particle flow was analyzed, in an internally circulating fluidized bed having several chambers, ill which solid circulation rate was controlled by changing gas velocity supplied to each chambers solid circulation rate in a 4 MWth test plant for all internally circulating fluidized bed gasifier (ICFG) was predicted fairly well from experimental data for I I scale ratio cold model. The solid circulation rate in an internally circulating fluidized bed is affected by the particle plunge by splashy the restricted resistance at the opening and the bed viscosity around the opening, Based ton the pressure balance around an opening, a mathematical model to predict solid mass flow rate was, developed, The model developed in this paper was well validated by the observed Values of ICFG hot model test data.