Abstract: In order to better understand the sunflower black stem the onset of diseases in different regions of the domestic situation and pathogenicity, from Jilin, Inner Mongolia, Hebei, Xinjiang sunflower black shank of a serious plot separation process for 18 strains. By using the method of traditional biology sunflower black stem bacteria （Phoma maodonaldii Boerema） main biologica} characteristics and systemic research on the pathogenic characteristics. With ITS universal primers ITS1 / ITS4 of rDNA - ITS area of strains for PCR amplification and sequencing, and the morphological identification of the bacteria, compare to pathogenic bacteria in different parts of the black stern force strength, the results showed that the bacteria to McIntosh stem point mi｜dew Phoma macdona~dii, separation of 18 strains were all black shank of pathogenic bacteria, and the strongest form of which was from Yangsi village of Inner Mongolia Ulanqab, And the weakest was from Baicheng of Jilin province academy of agricuhural sciences＂ plots. This study aimed at providing a better master black stem pathogen biology characteristics and targeted to provide basis for prevention and treatment of the disease.