The invention relates to the technical field of gene engineering, in particular to a Coat gene of nervous necrosis virus of grouper, an expression method in colibacillus and application. The gene of the nervous necrosis virus of the grouper has the advantages that the Coat gene of the nervous necrosis virus of the grouper is obtained to fill the blank of study on the Coat gene of the nervous necrosis virus of the grouper; the sequence of the Coat gene of the nervous necrosis virus of the grouper is artificially synthesized or biologically synthesized by transgene into recombinant protein with biological activity, so that the gene of the nervous necrosis virus of the grouper is acknowledged to prepare a vaccine; by using the gene engineering vaccine, the usage amount of medicine in the culture production is greatly reduced, so as to fundamentally eliminate the hidden hazard of medicine residues in aquatic products, and provide a health and high-quality green aquatic product for consumers.