The work aims to improve the accuracy of color reproduction quality assessment in online detection, and construct color difference calculation model of online print detection based on iCAM model. The images of printing samples obtained by CCD camera in the online detection system were divided according to the ink zones. Online color difference detection model was established based on iCAM model and IPT uniform color space, and then the color difference of every ink zone was calculated. Visual psychophysical experiment was designed to evaluate the color reproduction quality of every ink zone. STRESS value was used to evaluate the consistency between the color difference calculated by iCAM color difference detection model and the visual perception color difference. The color difference was also compared with the one calculated by CIELAB model, in order to verify the online color difference prediction accuracy of the model based on iCAM. The color difference model calculations based on iCAM had higher visual consistency, more in line with the visual evaluation results, and it had higher accuracy of online color difference detection compared with the traditional color difference model. Online detection color difference calculation model based on iCAM takes into account the spatial characteristics of human vision and chromatic adaptation, suitabled for complex observation conditions. It can improve the accuracy of online color difference detection; therefore, it can be used for online detection and evaluation of print color reproduction quality in actual printing production.