In order to further improve the detection rate of foreign fibers in cotton, the application of optical imaging technology in foreign fiber detection was explored. The principle and detection effect of ultraviolet, X-ray, linear laser, polarized light, infrared light and hyper-spectral imaging technology were evaluated and analyzed on the advantages and limitations of the various imaging methods, and the existing problems and deficiencies in the current research were summarized. It is considered that different imaging
methods should be applied to detect different types of foreign fibers, and it is not possible to detect all types of foreign fibers at the same time. Moreover, the multi-camera imaging scheme and the improvement of camera resolution are found to increase the redundant information of images and affect the detection speed. At the same time, most of the testing methods are only verified under laboratory conditions and are short of verification in actual production environment. It is pointed out that the future research should focus on multi-camera multi-light source imaging scheme, and should work to reduce the redundancy of image information. Light sources should be reasonably selected on type, quantity, power and installation mode, and an automatic parameter adjustment system should be developed for imaging systems.