The use of residual organic matter content in the evaluation of high mature or over mature source rocks or the prediction of oil and gas resources may lead to wrong conclusions. Therefore, it is essential to restore the original organic matter. There is a good correlation between the content of original organic matter and Mo/Al ratio in hydrostatic anoxic sedimentary environment, so the Mo-TOC correlation estimation method is a new method for the recovery of original organic matter content, which is simple and convenient, and suitable for the analysis of a large number of samples. In this paper, the black rock series of Qiongzhusi Formation of lower Cambrian in Huize area, east Yunnan province is taken as an example to try to recover the original organic matter content of this highly maturated shale with a new method. The results show that there is a large deviation in the calculation of the four regression equations, which is due to the lack of a large number of cases for statistical regression. The variation trend of the four curves drawn according to the calculation results is consistent and highly correlated with the sedimentary environment and lithology. The finer the particle size, the darker the color and the higher the organic matter abundance. After recovery the content of original organic matter was at least 3.20% and at most 8.04%, with an average of 4.24%. It indicates that Qiongzhusi Formation black rock series in this area has a high abundance of organic matter and is a high-quality source rock, which can be used as the potential horizon of shale gas exploration area for further evaluation.