Nowadays, knitted fabrics made of two-tone mélange yarns have been widely used for producing prevailing athleisure wear. There are a lot of quality disputes because the color matching deviation of using the spectrometer is so high that it can only be visual tested, resulting in low color matching accuracy, and a variety of patterns can be made as the knitting conditions change. By way of measuring the color ratio via high-power microscope, this study is focused on analyzing the color ratio between the face side and back side for the tested fabric samples. First of all, four different knitting conditions are respectively used for making greige fabrics, which are all made with the same melange yarn—round-cross section, semi-dull 145D/192F. Then, all of the four greige fabrics proceed from pre-treatment, dyeing(for Nylon only), to finishing. All of the process throughout the same batch. Then, a microscope, especially served as the fabric image analysis system, is used to measure the color ratio and calculate the difference between both sides of these samples. It indicates that the color ratio of the two kinds of yarns shows a strong negative correlation and there is a strongest correlation between the fed-in tension and color ratio difference. It demonstrates that the method of coverage rate analysis can precisely calculate the color ratio of yarns, and it can be the important reference of color matching operation. The records and adjustment of fed-in tension can reduce quality disputes and improve production reproducibility