Abstract: Detecting carton with cigarette pack missing by its weight fails to identify the fault carton exactly,therefore a detecting system based on X-ray was designed.The system comprises a soft X-ray generator,a first receiver for receiving top layer cigarette packs,a second receiver for receiving bottom layer cigarette packs,and a single chip microcomputer;it adopts synchronized signals to monitor cigarette packs entering into data collecting area.200 data per cigarette carton(100 each for top and bottom layers of cigarette pack) are real-timely collected by an A/D adaptor,and the data are compared and analyzed against the benchmark and standard value,the main controller will release a "stop" or "rejection" signal in case a cigarette carton with pack missing is going through.The actual running results showed that comparing with carton weighing detector,the detection rate of pack missing carton of the new system increased from 94% to 98% and rate of wrong rejection decreased from 11‰ to less than 5‰.