Abstract: In 2016, the National Nuclear Safety Administration of China issued the nuclear safety regulation for the design of nuclear power plants (HAF 102—2016), which proposed the goal of “technically realizing the offsite protective action to reduce radioactive consequences is limited or even can be eliminated”, but did not give the corresponding acceptance criteria. The criterion of limited impact (CLI) proposed by European utility requirement (EUR) for the design extension condition provides a general simplified judgment method, which has been adopted by many European countries. Since EUR does not disclose the determination method for determining the environmental impact coefficient of CLI, some research institutes in China have conducted a lot of research and discussed the applicability of CLI in Chinese plant sites. Some of them have given the calculation formula and corresponding coefficient of CLI for China. Based on the existing research results, through the discussion of the CLI design concept, in this paper it is argued that: 1) The criteria in the CLI expression establish a relationship with the offsite emergency protection action; 2) The essence of CLI expression is to give a simple formula for calculating the offsite radioactive consequences, that is, the radioactive consequences caused by all radio nuclides are calculated by the release activity of 9 representative radio nuclides. Based on the understanding of the CLI concept, it was attempted to revise the previous CLI coefficient derivation formulas in this paper, and based on a more realistic analysis method for source term and radioactive consequences of severe accident, a new method for determining the environmental impact coefficient of CLI was proposed. The core difference between this method and the previous method is that the ratio of the radioactive consequences caused by the nuclide group to the release amount of the representative nuclide in the nuclide group is used as the environmental impact coefficient of the representative nuclide. Based on the design parameters of HPR1000 and the site conditions of Zhangzhou Nuclear Power Plant, and referring to CLI-1 in EUR RevD, the goal of no evacuation outside the nonresidential area (600 m from the reactor) was proposed, and the relevant environmental impact coefficient with the method proposed was deduced in this paper. The results show that the environmental impact coefficient determined by this method is similar to the correlation coefficient given in EUR, which proves that the method is more credible, and the method can be further extended to other plant sites in China, and can be used to establish the CLI for China.