The flow character of the back-feeder is important for the stable operation and continuous running of CFBs. In this paper, the numerical simulation research for the back-feeder is carried out. The solids concentration profiles in the standpipe and back-feeder are obtained. The influence of the aeration flow rate on the flow pattern and the flow stability is researched. Under the working conditions, the consistence of the flow character between the simulation and the experiment proved the practicability of the mathematic and physical models in this simulation.