Abstract: An SNP molecular marker for weight gain trait selection and genetic sex identification of Ictalurus punctatus as well as a screening method and application of the SNP molecular marker are provided. At least one of 17 SNP molecular markers for weight gain trait selection of Ictalurus punctatus and a molecular control means for genetic sex and weight gain trait selection and control of Ictalurus punctatus are further provided. Efficient and scientific identification of Ictalurus punctatus is achieved by means of simple PCR reactions and nucleic acid test strips, and the accuracy rate reaches 100%. A traditional agarose gel electrophoresis method is not used in the whole identification process, the cumbersome steps of gel preparation and running electrophoresis are omitted, nucleic acid dyes are not used, and the experimental process is safe and environmentally friendly.