Total RNA was extracted from Sclerotinia sclerotiorum NGA₄ mycelia and used as the template to amplify the full length of cDNA of SsXYN gene by RT-PCR, and the gene fragment was subsequently cloned into pMD19-T vector. The results of bacterial colony PCR, enzyme analysis and sequencing analysis indicated that the S. sclerotiorum SsXYN gene was successfully cloned. SsXYN gene was digested completely from pMD19-T : SsXYN by BamH I and Sal I, and then was cloned into expression vector pET32a. The results of bacterial colony PCR and enzyme analysis showed the expression vector pET32a : SsXYN was successfully constructed. After that, the recombinant expression vector was carried into E.coli BL21 by heat-shock transformation, and the strain of E.coli BL21 carrying SsXYN gene was obtained. The study provides a basis for our understanding of the elicitor SsXYN downstream signaling pathway in plant immunity.