The purpose of this paper is to obtain a coating structure with stable structure and bright color on the silk substrate. Monodisperse SiO2@PDA microspheres were used as the precursor to construct SiO2@PDA photonic crystals on the silk. The effect of chitosan solution with different mass fraction of chitosan on the color fastness of structured colored silk was investigated. The microstructure of SiO2@PDA photonic crystals was observed by field emission scanning electron microscopy (SEM), the elemental composition of SiO2 microspheres was characterized by energy dispersive spectroscopy (EDS), the phase structure of SiO2 and SiO2@PDA microspheres was characterized by X-ray diffraction, and the color fastness of structural colored silk was investigated by friction test and washing test. The results show that the SiO2 and SiO2@PDA microspheres prepared in this experiment have uniform particle size and good monodispersity. The structures of SiO2@PDA photonic crystals are closely and periodically arranged. Compared with the structural colored fabric which has not been treated with chitosan solution, the structure color of the fabric treated with 3% (mass fraction) chitosan solution has less shedding after tribological test and water washing test, and still keep its original color. The results show that chitosan solution treatment can improve the color fastness of colored fabric effectively.