Abstract: The total organic carbon (TOC) is one of the key parameters in shale gas reservoir evaluation, it is not only the material basis of shale gas, but also an important carrier of shale gas. Take Shanxi Formation in Erdos Basin as an example, the shales are divided into four different types with different colors: black coal, gray black shale, gray shale, gray white siltstone, then four different color values are given to calculate total color assessment(TCA) of shale and fit the relationship between TCA and measured TOC. The results show that the calculation of TCA is positively correlated with the measured TOC, the correlation coefficient (R²) of exponential fitting and three square fitting is the highest, the calculation of TOC is very close to the measured TOC. Therefore, we can quickly calculate the TOC of shale by using the method in the outdoor work, which provides the reference for the optimization of target zones for shale gas.