Abstract: In order to be able to timely issue an early warning of plugging of the pipe connecting the first and second stages of the cyclone to guard against occurrence of severe accidents, a study is made of the change of the feed inlet pressure of the cyclone when its connection pipe is blocked up. Based on the result of study, a plugging alarm and control system is developed. The system can perform real-time monitoring of the feed inlet pressure and its limiting pressure value can be set through the interface of central processor. At the moment when the pressure reaches its upper limits the system can latch up the feed inlet and at the same time, the interface of the central processor and the phonetic system will give prompting information, so as to control the occurrence of accident within a minimum extent and reduce the trouble-shooting time.