[Objective] Sichuan is an area the most typical of concentrated distribution of purplish soil in China. For this paper, a total of 100 samples were collected from 30 typical purplish soil profiles widely distributed in Sichuan Province for analysis in an attempt to explore quantitative relationships of colorimetric parameters of purplish soil with forms of iron and manganese, and organic matter.[Method] The samples were subjected to color measurement and chemical analysis in the laboratory for determination of Munsell HVC, CIE L*a*b* colorimetric parameters, content of iron and manganese by form (total Fe_t/Mn_t, free form Fe_d/Mn_d, amorphous form Fe_o/Mn_o and organic-bound form Fe_p/Mn_p) and content of organic matter. Correlation analysis and stepwise regression analysis of the data were performed to specify quantitative relationships of colorimetric parameters of the purplish soil with forms of iron and manganese, and organic matter therein.[Result] Results show that organic matter content in the purplish soil is significantly and negatively related only to C, a* and b*, but not related at all to H, V and L*. Content of iron and manganese in the purplish soil is closely related to color of the soil. Fe_t, Fe_o, Fe_p, Mn_t, Mn_d and Mn_o are significantly correlated with colorimetric parameters of the two color systems. Pearson correlations of manganese of all forms, except for organic-bonded form, with colorimetric parameters are higher than those of iron of all forms in coefficient, and so are one-way fitting determination coefficients of manganese of all forms with colorimetric parameters. Determination coefficient R² of stepwise regression fitting of the joint effect of iron, manganese and organic matter on color of the purplish soil varies between 0.46 and 0.54.[Conclusion] Manganese content has an extremely important effect on purplish soil, which is "purple" in color. The soils derived from the purplish parent rocks that are relatively high in manganese content are slightly purple in color. Compared with the effect of iron or manganese alone, the combined effect of iron, manganese and organic matter exhibits a higher degree of regression fit with the two color systems.