Abstract: As required by the national regulations, the effluent discharge optimization work must be carried out by every NPP in China, and it is a typical comprehensive and complex decision-making problem, and multi-attribute utility method has been applied to the effluent discharge optimization of NPPs. For the application of multi-attribute utility analysis method, the effectiveness and rationality of the optimization result is based on the appropriate value of weighting factors. During the research of this paper, the factors involved in the multi-attribute utility method application to the optimization of liquid effluent discharge of NPPs has been successfully improved by introducing the impact of ecological radiation as an influencing factor into the process. The investigation of multi-factor weighting factors in the multi-attribute analysis and decision-making process was carried out using expert scoring questionnaires with the experts from various organizations during the research. The variation of the degree of attention to the factors of concern up to date in effluent discharge has been obtained. As the investigation results of this study show, the impact of ecological radiation shall be considered during the effluent discharge optimization study not only to meet the national regulatory standards requirements but also to give answers to the important issues of social concern. According to the result of investigation of multi-factor weighting factors, it is shown that the attention to the impact of NPPs on the public, the environment and public psychology has increased significantly. The purpose of this paper is to improve the application of multi-attribute utility method based on involving more factors and newly investigated multi-factor weighting factors, and to carry out the research on inland and coastal NPPs to prove technical bases for future NPPs discharge optimization. The effluent discharge optimization work of NPPs in China has been carried out for coastal NPPs. The paper took the lead in carrying out the discharge optimization work of inland NPPs in China, and the comparison between the results of inland and coastal NPPs shown that the discharge requirements of inland NPPs discharge is more stringently, and should be paid more attention in the future design and construction. The results, which provide a basis for further effluent discharge optimization of coastal and inland NPPs, are of good value in engineering application and scientific research.