Abstract: Present paper aims to introduce the process optimization of the semi-automatic fluorescent penetrant inspection line for large batches of small-size pipe fittings. Under the premise of ensuring the sensitivity of penetrant detection, the penetrant inspection process has been optimized by considering all its aspects such as the lifting of the rack, the drying method, the dripping time, the cleaning method, the cleaning time, the supplementary cleaning method, and the display. Improvement in detection efficiency was achieved and the consumables and the overall cost were reduced. Other improvement includes the increment of detection results and detection sensitivity, and it is also effective in controlling the pollution.