Abstract: Most of the initial in-place and undeveloped OOIP are low-grade reserves, and how to evaluate their potential is an urgent problem. There are many uncertainties in low-grade reserves, such as complex geological conditions, strong reservoir heterogeneity, limited data and limited geological knowledge. The reliability of the conventional evaluation method is poor. Therefore, a series of systematic evaluation methods for initial in-place and undeveloped OOIP on the basis of quantitative uncertainty was proposed, which mainly focused on three improvements. Firstly, the range value was used to describe the uncertainty of OOIP, which changed the unique value estimated by the certainty method in the past. The degree of certainty was proposed to quantitatively characterize the risk of reserves. Secondly, the evaluation index system, the evaluation method and the evaluation process of uncertainty of the key parameters were established. Thirdly, the new method was changed from the previous emphasis on reserve scale to reserve value, established a three-factor model of "the degree of certainty-unit reserves/resources value and the scale of reserves/resources" by applying risk-value assessment technology. Potential blocks were divided into four categories, namely type Ⅰ with low risk and high value, type Ⅱ with low risk and low value, type Ⅲ with high risk and high value, and type Ⅳ with high risk and low value. In this way, a potential evaluation platform combining reserves, production and value evaluation was proposed. The application of the method showed that it can effectively evaluate the reserve upgrading and development potential and optimize the blocks, and the selected blocks are basically consistent with the subsequent upgrading and development of potential blocks, which verified the reliability and rationality of the method.