In order to clear the relationship of pigment and dry matter content with flesh color of sweetpotato, and provide estimation methods for pigment content based on the RGB characteristic values of images, the carotene content in 240 strains, anthocyanin content in 234 strains, the relative dry matter content and RGB characteristic value were determinated. The results showed that the correlation coefficient of carotene content with RGB value was -0.913, and their partial correlation coefficient was -0.872, while the correlation coefficient of anthocyanin content with RGB value was -0.838, and their partial correlation coefficient was -0.836, indicating that pigment content was a determining factor and high positive correlation with root flesh color, however there was a closer relationship between carotene content and root flesh color. The correlation coefficient of dry matter content with carotene RGB value was 0.597, and their partial correlation coefficient was 0.273, while correlation coefficient of dry matter content with anthocyanin RGB value was -0.273, and their partial correlation coefficient was 0.255, indicating that dry matter content had very obviously negative effects. But in low carotene (about 3 mg/100gFW or less) group with the RGB value> 200, the partial correlation coefficient of dry matter content with RGB value was -0.0066 (P = 0.9426), so dry matter content had no effect on root flesh color of low carotene strains. The pigment content estimation achieved good fitting results using the quadratic polynomial regression model with R value, G value, B value, and dry matter. Multiple correlation coefficients of fitting equations in low carotene group with RGB values < 200, high or moderately high carotene group with RGB values ≥200, and anthocyanin group, were respectively 0.982, 0.975, and 0.937, indicating that the fitting values had close relationships with measured values, and their fitting values could reach respectively about the accuracy of 90%, 83%, and 86%. Therefore, the RGB characteristic value might be used as not only a good indicator of pigment content difference on varieties, but also a relatively accurate estimation for their pigment content, it could provide a convenient and objective evaluation method of pigment content for large sums of samples in the early-generation selection of sweetpotato.