Sunflower Verticillium wilt is a typical soil-borne disease and one of the major diseases that affect sunflower production in China. This study is centred essentially on the isolation and identification of genetic diversity in the same field. A theoretical foundation was established for controlling sunflower Verticillium wilt. In this experiment, 33 plants infected with sunflower Verticillium wilt were collected from the same field in Sandaozhangfang village Wengniute county Chifeng city. The sunflower plant DNA was isolated and subjected to PCR molecular identification by using specific primers of V. dahliae，the pathogen was preliminarily identified as Verticillium dahliae. Three strains of pathogens were randomly selected and sequenced with ITS1/4; these sequences were compared with internationally accepted V. dahliae sequence to confirm the PCR identification result. The morphology of the pathogens was observed, the results showed that the colony morphology of the strains on the PDA medium was slightly different but conidia and conidiophore had no difference. The PCR identification of strains by using specific primers of Verticillium wilt with different race types and mating types showed that all strains were NO2 race type and MAT1-1-1 mating types. IGS sequence analysis was done using the maximum likelihood method, contrast and construct a phylogenetic tree of Verticillium dahliae. This research work revealed that the sequence difference among the 33 strains were very small, all could be grouped into one major category. Also, the results showed that the strains from the same site showed pathogenicity to the host, and there was pathogenicity differentiation, but the degree of differentiation was small.