OBJECTIVE To study the distribution characteristics of lactobacillus in the vaginal mucosa of patients with HPV infection. METHODS The planting density of lactobacillus in vaginal secretions of 95 cases with HPV16/18 infection and 90 cases of normal women of childbearing age were observed by oil microscope. And the strains of vaginal lactobacilli in two groups were analyzed using species-specific polymerase chain reaction (Species-specific PCR) and the distribution of vaginal lactobacilli in patients with HPV16/18 infection were investigated. RESULTS In HPV16/18 infective groups, the planting density of lactobacillus in the vaginal mucosa was 104 (68-186)/HP. It was significantly lower than that of the normal group (234 (161-326)/HP, P<0.05). Compared with the normal group, the positive rates of lactobacillus iners, lactobacillus crispatus, and lactobacillus gasseri were significantly lower in HPV16/18 infection group (P<0.05). CONCLUSION The HPV16/18 infection is associated with the decreased number of lactobacillus and the imbalance of vaginal flora; Lactobacillus iners, lactobacillus crispatus, and lactobacillus gasseri may play a key role in maintaining the vaginal micro ecological environment.