Regarding to the fact that sampling analysis techniques compromise the integrity of the invaluable and nonrenewable cultural relics, the non-invasive identification method, based on visible spectroscopy, was proposed to identified the chemical composition and particle size information of the pigment used ancient murals. A non-contact acquisition platform was established to measure the visible spectrum of the ancient murals. A visible spectral database of the pigment was developed as the reference. After the analysis of the spectrum in the database, the non-invasive identification process and method were constructed based on visible spectroscopy to identify the chemical composition and particle size information of the pigment used ancient murals. First, the geometric feature of the visible spectrum was extracted to construct the feature space for chemical composition identification, and then the amplitude feature of the visible spectrum was integrated and fitted with the mean particle size for particle identification. The method was tested using the murals in Mogao Grottoes.