A vision-based inspection system was proposed to inspect the quality of in-vitro diagnostic kits in the assembly line. System workflow and hardware structure was determined after defects analysis. The procedure to inspect major defects of strip and kit was determined by the application of image processing and analysis techniques such as image enhancement, edge detection, threshold segmentation, and morphology. Experimental results show that the proposed system accuracy is above 98%.The vision system can be a good substitute for manual inspection and improve the inspection efficiency and product qualification rate effectively.