This article aims to clarify the coloration mechanism of butterfly wings, and apply it on textiles dyeing and printing, to solve the problem of high water consumption and heavy pollution in textile industry. Two butterflies living in temperate zones were studied, which are Limenitidini and Sasakia charonda. SEM was used to observe the microstructure of two areas of each butterfly. It is found that there is non-smooth surface on wing scales, such as spinal veins, cross-rib, etc. Ocean USB2000 UV-vis-NIR micro spectrophotometers was used to perform multi-angle spectral tests on four areas, and it was found that only the purple part of Sasakia charonda showed the phenomenon of wave crest shifting with angle, which is characteristic of structural color. Then ethanol was used instead of air as mesenchyme of purple area, and the color changed, which verified the photonic crystal structural color mechanism. At last, a photonic crystal model was established based on the microstructure of the purple part of Sasakia charonda, and the band gap was calculated using the plane wave expansion method. Then the relationship between color and band gaps was analyzed.