In August 2014,a disease that caused severe losses on sorghum plants in farmland of Inner-Mongolia University for the Nationalities at Tongliao,Inner-Mongolia,China was found.Different pathogenic strains were isolated from symptomatic sorghum leaf tissues.Morphology,biological characteristics,pathogenicity and ITS and EF-1α sequences of these pathogenic strains were analyzed.Based on the morphological features,pathogenicity,sequence similarity of ITS and EF-1α,these pathogenic strains were identified as Alternaria alternata.