The invention discloses a medicinal injection for killing coral predator acanthaster planci. The medicinal injection for killing the coral predator acanthaster planci contains Vibrio alginolyticus, Vibrio parahaemolyticus and a culture medium. The Vibrio alginolyticus HN492 and the Vibrio parahaemolyticus A16 in the medicinal injection for killing the acanthaster planci are separated from a seawater environment, are harmless to the environment under conventional concentrations, do not belong to pathogenic strains, and do not have pathogenicity for marine animals of marine fishes, shrimps, acanthaster planci and the like. According to the mechanism of the medicinal injection of killing the acanthaster planci, the bacteria form ultrahigh concentrations in acanthaster planci bodies locally, various enzymes and metabolites which are secreted by the bacteria cause damage to tissues in the acanthaster planci bodies, and a large amount of bacterial protein causes stress for the acanthaster planci, and causes death at last.