The invention discloses an application of an arabidopsis transcription factor gene BP in regulation of plant seed germination. An arabidopsis transcription factor gene BP encoded transcription factor BP is a member of an I-class KNOX subfamily and serves as a positive regulation factor to participate in a PHYB mediated light initiating seed germination process; T-DNAs (transfer-deoxyribonucleic acids) of the transcription factor gene BP are inserted into mutants bp-1 and bp-9 for inhibition of seed germination, the seed germination rate is obviously increased after overexpression of the transcription factor gene BP, and the situation shows that the transcription factor gene BP plays an important role in the seed germination regulation process. According to the application of the arabidopsis transcription factor gene BP in regulation of the plant seed germination, a mechanism of PHYB-dependent seed germination regulated by the transcription factor BP is disclosed, an application direction of the transcription factor gene BP in plant species improvement is provided, and the important value for cultivation of a transgenic plant with high germination rate is realized.