A novel K (capsular antigen) serotype of Vibrio parahaemolyticus and an application thereof are provided. A novel K (capsular antigen) serotype of Vibrio parahaemolyticus, which was deposited at the China General Microbiological Culture Collection Center (Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing) on Feb. 20, 2019, with a deposit number of CGMCC No. 17249, wherein the K epitope of the Vibrio parahaemolyticus has a sequence set forth in Sequence No. 1. The novel K serum is highly specific, and can be used to conveniently and quickly detect a novel K serotype of Vibrio parahaemolyticus (O4:KUT-recAin) which has a rising infection rate in recent years. It provides important detection techniques for the pathogen diagnosis, monitoring and prevention of infectious diarrhea.