Objective：To observe the effect of periodontitis vaccine adjuvant interleukin-15（IL-15）on the proliferation of B lymphocytes in the mesenteric lymph nodes of SD rats，and explore the possibility of using IL-15 to improve the immune effect of gene vaccine. Methods：SD rats were immunized with nasal spray of the periodontitis gene vaccine pVAX1-HA2-FimA/IL-15（group A），pVAX1-HA2-FimA（group B），and normal saline（group C）. Then mesenteric lymph node B cells were isolated and purified by magnetic bead sorting method，the number of B cells was detected by CCK8 method，the relative expression level of CKs2 gene was detected by RT-qPCR，and the expression level of specific IgA in culture medium was detected by ELISA. Results：The proliferation level of B lymphocytes in group A was higher than those in group B and group C（P < 0.05）. The relative expression level of CKs2 mRNA of B lymphocytes in group A was higher than that in group B，but the difference was not statistically significant（P > 0.05）. The level of specific IgA secreted by B lymphocytes in group A was higher than those in groups B and C（P < 0.05）. Conclusion：IL-15 is an effective gene vaccine adjuvant to promote the proliferation of B cells and increase the expression level of specific IgA antibodies in the periodontitis gene vaccine constructed by our team.