Abstract: Based on the situation that the existing domestic temperature control standards are not performable, the preliminary study on the acceptability of the mixing zone scope of thermal discharge for nuclear power plant was conducted in this paper, taking a coastal power station SNP as a case. The following preliminary conclusions could be drawn from the results of cluster analysis of the SNP site under different results of mathematical modeling and physical model test: 1) The influence intensity of ecological function of the SNP site seawater is small and the scope of thermal discharge mixing zone is acceptable under SNP-1 (Unit 1 and 2) operating condition; 2) the influence intensity of ecological function of the SNP site seawater is small and the scope of thermal discharge mixing zone is acceptable in spring under SNP-1 (Unit 1 and 2) and SNP-2 (Unit 3 and 4) operating condition, while the influence intensity of ecological function of the SNP site seawater is large and the scope of mixing zone is unacceptable in autumn under the same operating condition.