We found a male-sterile plant, named “72A”, in the GX–49 strains (Brassica napus L.) in Hunan Agricultural University experimental field in March, 2011 (Changsha, Hunan, China). During its abortion stage we observed its anther development carefuuly by using the technology of paraffin sections. Through the dynamic analysis of its genetic characteristics after it was hybridized with double-low, early maturity Brassica napus GZ–4 and GZ–20–2, we found that 72A belonged to no pollen sac abortion type and its recessive genic male-sterile character was controlled by a single.gene.