In this research,the rapeseed rapid alkalinization factor gene RALFbn was initially cloned from Brassica napus by the NCBI (National Center of Biotechnology Information) database information.Structure analysis of RALFbn,its predicted protein RALFbn and the expression of RALFbn were done.The results showed that:(1)The full-length cDNA of RALFbn in B.napus was 510 bp,no intron,encoded 79 amino acids.(2)The RALFbn protein had the conserved “YIXY” domain and four conserved Cysteine residues which were the characters of RALF family members.It also had N-myristoylation site,tyrosine kinase Ⅱ phosphorylation sit,protein kinase C phosphorylation site,tyrosine kinase phosphorylation site,which indicated an active physiological activity of the potential RALFbn.(3)RT-PCR analysis results showed that RALFbn mostly expressed in rape stamens,no expression in pistil,petals and sepals,indicating that RALFbn was closely related to pollen development of B.napus.