In this paper, pigments of a piece of Qing watercolors on Pith were tested by laser Raman spectrometer and super depth microscopy.The analysis indicate that the chromogenic substances of red pigment is minium, the chromogenic substances of blue pigment is ultramarine, the chromogenic substances of black pigment is carbon black, the chromogenic substances of white pigments are calcite and hydrocerussite, the chromogenic substances of green pigments are malachite and emerald green.The chromogenic substances of yellow pigments needs further testing.Ultramarine and emerald green are synthetic pigments and the first synthesis time was 1830 and 1814 respectively.Emerald green was not used in Chinese painting until the 1950s, and it was concluded that this piece of Qing watercolors on pith was possibly drawn after the middle and late Qing Dynasty.This study shows that LRS is ideal and powerful tools for nondestructive identification of pigments on Qing watercolors on pith due to the plant cell structure of the Qing watercolors on pith paper and the particularity of cultural relics.The technique has broad application in preservation and restoration of cultural relics.