The clogging problems of pneumatic fly-ash removal system has seriously affected the safety operation of power plants. Based on an extensive investigation, the causes for clogging problems of pneumatic ash removal system is analyzed and categorized, and it is concluded that the insufficient pneumatic fly-ash removal capacity caused by variation of ash properties is the key factor for the clogging problem. The actual factors that lead to the clogging problem of fly-ash removal system are analyzed and corresponding solutions are proposed, and some proposals are put forward on how to avoid the clogging problem of pneumatic fly-ash removal system.