To understand the expression characters of BnPMEI1 gene in Brassica napus we cloned the gene from Xianyou 15 with the high resistance to Sclerotinia sclerotiorum and 98C40 with high sensitivity to S. sclerotiorum by PCR. Then the sequences were subjected to bioinformatics anlysis and expression in bacterial host. Sequence analysis showed that the coding region of the gene was full-length 615 bp, encoding 204 amino acids, with a signal peptide and a PMEI domain, belonging to the PMEI family gene, named BnPMEI1(GenBank accession number is ON254917). Expression analysis showed that BnPMEI1 was expressed in root, stem, flower, leaf, pod skin and grain, but the expression was the highest in leaf and the lowest in root, and the expression in stem, leaf and flower of Xiangyou15 were significantly higher than those of 98C40. Under the treatment of S. sclerotiorum, methyl jasmonate(MeJA) and salicylic acid(SA), the expression of BnPMEI1 in Xiangyou15 was up-regulated, while that in 98C40 was inhibited; under ethylene treatment, the expression of BnPMEI1 in both varieties were down-regulated, and the down-regulation was more significant in Xiangyou15. The results of inoculation in vitro showed that the disease spot of rape mutants overexpressing BnPMEI1 was significantly smaller than that of wild-type leaves. Comprehensive analysis showed that BnPMEI1 gene might be regulated by SA and jasmonic acid pathway, which induced the resistance of B. napus to S. sclerotiorum.