Abstract: The role of Propionibacterium acnes in the pathogenesis of acne has attracted more and more attention.Recent studies have demonstrated that there is a significant difference in the type of Propionibacterium acnes distributed in the skin between acne patients and healthy volunteers.Propionibacterium acnes type Ⅰ exists most frequently in patients with acne, while types Ⅱ and Ⅲ exist in healthy volunteers.This difference in Propionibacterium acnes strains is also reflected in the pathogenesis of acne.In addition, the genome sequences are different between different types of Propionibacterium acnes.Due to the lack of the intact defense system CRISPR, Propionibacterium acnes type Ⅰ show characteristics of some pathogenic genes, and have a stronger pathogenecity than the type Ⅱ strains.Moreover, there may be competitions between Propionibacterium acnes types Ⅰ and Ⅱ, and the dominant type may determine whether acne occurs.These findings may offer new ideas for further studies on the role of Propionibacterium acnes in the pathogenesis of acne and for acne treatment.