Chitin is the third polysaccharide component of the wall,which was encoded by several chitin synthases (chs) genes,has been detected in Aspergillus fumigatus.The family of chs genes in Aspergillus fumigatus includes at least seven different genes.But whether chitin synthase gene chsC plays a role in the lifestyle,appearance and sensitivity to antifungal drugs in Aspergillus fumigatus is unknown.In our study,we constructed a binary vector pDHt/SK of Agrobacterium tumefaciens,which includes the positive selected mark --the hygromycin resistance cassette,targeted chitin synthase gene chsC of Aspergillus fumigatus and transformed it into Aspergillus fumigatus by Agrobacterium tumefaciens-mediated transformation.The positive transformant was selected by hygromycin resistance cassette and identificated by RT-PCR.The lifestyle,appearance and sensitivity to antifungal drugs of the mutant were compared with the wild type Aspergillus fumigatus.The result of RT-PCR showed that chitin synthase gene chsC was clearly inactivated.The growth velocity of the ChsC- mutant was obviously slower than the wild type A.fumigatus.Long conidia chains and uniformity hypha of the chsC- mutant were observed,especially some enlarged hypha in some section.The sensitivity of the chsC- mutant to terbinafine was more sensitive than that of the wild type A.fumigatus.Agrobacterium tumefaciens-mediated transformation can target to disrupt and inactivate the targeted gene of Aspergillus fumigatus.The chsC gene contributes to the lifestyle,appearance and sensitivity to antifungal drugs in Aspergillus fumigatus.