To investigate the changes in characteristics of periodontal pathogens in subgingival plaque of patients with puberty gingivitis and its relevance with clinical symptoms.A total of 108 subgingival plaque samples were collected from 30 patients with puberty gingivitis (Group G), 9 cases of chronic periodontitis (Group P) and 15 healthy controls (Group H). The age of the 54 participants was from 11 to 17. The black-pigmented bacteria (BPB), Fusobacterium nucleatum (Fn), Actinobacillus actinomycetemcomitans (Aa), Actinomyces were detected using bacterial culture. The probing depth (PD), gingival index (GI), bleeding index (BI) and attachment loss (AL) were also recorded.In all these three groups, the detection rates of black-pigmented bacteria were: 3%, 30% and 100%; Fn were: 30%, 68% and 94%, statistically significantly different (P < 0.01). The lgCFU/ml of black-pigmented bacteria and Actinomyces was higher in mild-moderate group [(3.8 +/- 0.7) and (5.3 +/- 0.9)] than in Group H (P < 0.001). The lgCFU/ml of black-pigmented bacteria and Fn significantly was higher in severe inflammation group [(4.7 +/- 1.2) and (4.4 +/- 0.8)] than in the mild-moderate group (P < 0.01). The lgCFU/ml of black-pigmented bacteria, Fn and Aa was higher in severe gingivitis group [(6.6 +/- 1.0), (5.5 +/- 1.0) and (4.2 +/- 1.7)] than in mild gingivitis group (P < 0.01). The detection rate and lgCFU/ml of black-pigmented bacteria, Fn and Aa were both positively correlated with BI, PD and AL.In the stage of severe gingivitis, the periodontal pathogens increased markedly, suggesting that risk of further destruction of periodontal tissue may exist.