A plant type related protein, and a coding gene and an application thereof are provided. The protein is: (a) a protein consisting of the amino acid sequence of SEQ ID NO: 1; (b) a SEQ ID NO: 1-derived protein having substitution, deletion, and/or addition of an amino acid residue on the sequence of SEQ ID NO: 1, and related to the plant type and/or inactivation of a plant brassinolide type, or (c) a protein having more than 80% homology to the sequence of SEQ ID NO: 1 and related to a plant type and inactivation of a plant brassinolide type. The protein and its coding gene have very important value in improving crop production, improving the visual enjoyability of a green plant, implementing simple cultivation of a plant and improving the breeding efficiency, and has a broad prospective in genetic improvement of a plant, new variety cultivation and an application.