Abstract: As a solution to the malfunctioning of plug wrap splice detecting device caused by paper dust contamination in ZL26 filter rod maker, a new splice detecting and rejecting device was developed with high-sensitivity photoelectric sensing technology. The device was mainly composed of a high-sensitivity infrared sensor and a bracket and combined with PLC program design. The bracket allowed a larger clearance between plug wrap and detecting device to reduce paper dust buildup and make cleaning work easier. The results of application showed that after improvement, the detecting device could effectively detect and reject defective filters with the response time less than 0.25 milliseconds. When ZL26 filter maker ran at a speed of 600 m/minute, the detecting device could effectively detect and reject the filter rod with a splice or containing a pulp piece larger than 3 mm, its detection accuracy reached 100%.