The invention belongs to the technical field of plant molecular biology, and particularly relates to a rape transcription factor BnWRKY184, a cloning method, a carrier, a host cell and an applicationto preparation of lignin-related transgenic plants. The nucleotide sequence of the rape transcription factor BnWRKY184 is represented as SEQ ID NO.1, the amino acid sequence is represented as SEQ ID NO.2, the length of the nucleotide sequence is 645 bp, and the length of the amino acid sequence is 215 amino acids. The provided rape transcription factor BnWRKY184 has a negative control effect, andcan directly overexpress to inhibit expression of plant lignin and cellulose synthetic genes, so that biosynthesis of lignin and cellulose is blocked, development of sclerenchyma is inhibited, the degree of lignification is reduced, and theoretical basis and related genes are provided for follow-up modification of lignin and cellulose content of rape and seed breeding of rape for vegetables, rapefor feed and rape for green manure.