For orderly and sustainable development, petroleum resources should be planned scientifically. Based on the discount cash flow (DCF) method, we propose a new approach for the comprehensive grading of petroleum reserves in China because existing reserve classification methods are unable to support the formulation of exploitation planning. This approach combines five factors: economic value, technological progress, subsidy policy, reserve scale and resource risk. Examples show that this approach can be used to grade natural gas resources rapidly and effectively, which is helpful for providing effective guidance for the scientific development of gas resources. (C) 2016 Elsevier Ltd. All rights reserved.