Abstract: In order to improve the quality of triple filter rods in batch production, an infrared photoelectric detection system was designed, which was composed of infrared light source, photoelectric receptor, digital signal processor, displayer and controller. Via detecting the variations of infrared light passing through the filter rod, the material in different sections of the triple filter rods was distinguished, and the defectives, such as gaps, phase deviation, section missing or out of alignment were detectable. The system was tested on an ITM SOLARIS filter combiner to on-line detect 46 000 triple filter rods of"cellulose acetate + paper + active carbon". The results showed that:1) The electric signal intensities detected by the infrared system were 254, 87, 16 and 580, for cellulose acetate, paper, active carbon sections and gap respectively; and the electric signal switches of the respective detectors were defined as ≥ 363, ≤ 40, 40-143, 143-363 separately. 2) The defective filter rods with gap ≥ 0.3 mm, phase deviation ≥ 0.3 mm, section missing or out of alignment were accurately rejected with the accuracy of 99.8%. The system realizes the on-line detection and rejection of defective triple filter rods, and promotes the stability of filter rod production effectively.