The work aims to pre-process the images with PCA image fusion algorithm for the visual detection system of FX-2 packaging machine, in order to solve the problem that it is difficult for a single visible or infrared camera to sim-ultaneously detect the presence, location, area and uniformity of the coating during the glue coating detection of cigarette packers in cigarette factory. The detection system needed to install an infrared camera at the glue coating detection site, and capture visible and infrared images at the same time. Then, a principal components analysis was conducted on the visible and infrared images. The images were fused after the principal components were replaced. Finally, the fused images were outputted to the back-end processing system. The experimental results showed that, the fused image contained rich texture details, edge information and temperature information, and had high contrast and detectability. PCA image fusion algorithm is very effective in the front-end processing of glue coating detection. After the fused image is processed in the back-end, it can quickly detect the presence, location, area and uniformity of glue coating on packaging paper. After the visual inspection system of FX-2 packaging machine is embedded, the unqualified packaging paper can be detected in real time.