Abstract: A thermosensitive hydrogel system consisting of PLGA-PEG-PLGA hydrogel and Pseudomonas aeruginosa DNA vaccine was constructed and the immune efficacy of the system was evaluated. The PLGA-PEG-PLGA thermosensitive hydrogel containing Pseudomonas aeruginosa DNA vaccine was prepared by a simple physical mixing method. The gelation temperature, cytotoxicity, and release curve in vitro were tested.The degradability of hydrogel in vivo was evaluated. The mice were divided into control group (PBS), hydrogel group (Hydrogel), in vivo-jetPEI/plasmid DNA group (in vivo-jetPEI/pDNA), and hydrogel + in vivo-jetPEI/plasmid group (Gel+in vivo-jetPEI/pDNA). Mice were immunized three times with a ten-day interval. Two weeks after the last immunization, the mice were sacrificed. The proliferation of splenic lymphocytes, serum specific IgG antibodies and IFN-γ in supernatant of splenic lymphocytes were detected. The gelation temperature of PLGA-PEG-PLGA hydrogel was (32 ± 0.5) ℃. There was no obvious toxicity to cells in vitro, and about 80% of plasmid DNA was released after 7 days in vitro. PLGA-PEG-PLGA hydrogel was biodegradable, and degraded almost completely after 15 days in vivo. The spleen lymphocytes proliferated; the levels of specific IgG antibodies and IFN-γ of in vivo-jetPEI/pDNA and Gel+in vivo-jetPEI/pDNA groups increased. The hydrogel could enhance the immune response induced by DNA vaccine.Results suggest that the thermosensitive hydrogel system consisting of PLGA-PEG-PLGA hydrogel and Pseudomonas aeruginosa DNA vaccine is a promising new strategy for the development of PA vaccine.