In our country, a distinguishing feature is to burn wide-size distributive inferior coal in circulating fluidized bed. So we should pay close attention to the problem of organizing combustion of coal with different size granule in fluidized bed. This paper inquires into the kinematical and aerodynamic characteristics as well as combustion characteristics of wide-size distributive coal particles. And several facts affecting to combustion of circulating fluidized bed are analyzed to compare to practice data. At last some suggestions of design and operation are provided.