Recognizing the critical role of oil and gas resources as strategic assets and acknowledging the increasing emphasis on green development and social responsibility driven by international energy agreements and the “dual carbon” strategy, this study addresses the urgent need for a robust employee evaluation framework within China’s petroleum sector. While existing systems often prioritize competence-based indicators, they frequently overlook the crucial aspect of employee Moral Quotient (MQ). This research focuses on developing and validating a holistic, scientifically grounded, multi-dimensional, and dynamic MQ evaluation index system tailored specifically for Chinese petroleum enterprises. The study employed a mixed-methods approach, integrating a comprehensive literature review, semi-structured interviews with industry experts, and robust quantitative techniques, including the Analytic Hierarchy Process (AHP) and the entropy weight method. A two-round Delphi study, involving 18 experts from six provinces across China, ensured broad representation and facilitated the construction of the evaluation index system and the determination of indicator weights. The Delphi process achieved a high degree of expert consensus, evidenced by a 100% questionnaire response rate in both rounds, expert authority coefficients of 0.851 and 0.879, respectively, and Kendall’s coefficient of concordance of 0.243 and 0.247 (p < 0.01), respectively, demonstrating strong reliability and scientific validity. The resulting MQ evaluation index system comprises eight first-level indicators and thirty-three s-level indicators, encompassing key dimensions of employee morality relevant to the petroleum industry. This comprehensive system provides a robust and objective tool for employee selection, training, performance evaluation, and career development within Chinese petroleum enterprises, supporting informed decision-making in human resource management and fostering a culture of ethical conduct and sustainable development. Furthermore, the developed framework offers valuable insights and serves as a potential model for petroleum enterprises and other resource-intensive industries globally seeking to integrate MQ assessment into their human capital management strategies.