Objective: To explore the lipid-lowering activity of Lactobacillus gasseri and further verify its effect on lipid accumulation in HepG2 cells and hyperlipidemic mice， respectively. Methods: In vitro， oleic acid supplemented-HepG2 cells were used as lipid accumulation model， and a total of 166 Lactobacillus gasseri were screened regarding the lipid-lowing activity quantified by multiple oil-red O staining， in which one strain bacteria， BDUP， most steadily and significantly inhibited lipid accumulation. The lipid packing and detected triglyceride(TG) content were further observed in HepG2 cells with treatment of Lactobacillus gasseri. To confirm the lipid-lowing activity of Lactobacillus gasseri in vivo， the hyperlipemic animal model was constructed using C57BL/6J mice with high-fat diet feeding， followed by oral administration Lactobacillus gasseri for 4 weeks. The bodyweight of mice was recorded once a week. On the 28th day， all mice euthanized， the blood and liver were obtained to assess lipid level， as well as weighed fat mass. Results: Three cycles of oil-red O staining-based screening showed that 61 out of 166 (36.75%) strains significantly inhibited lipid accumulation with at least 10% efficiency， while 5 strains (3.01%) elevated lipid deposition and the remaining 100 strains had no significant effect on lipid regulation. Next， one strain BDUP was chosen to confirm its activity in vitro and in vivo， respectively. Experimental results showed that Lactobacillus gasseri BDUP had remarkable effect on cellular lipid accumulation， compared with the comparison group. By in vivo study， BDUP protected against bodyweight gain and fat accumulation， and decreased the lipid levels of blood and liver caused by high-fat diet， so as to improve lipid abnormalities， with a higher efficacy than the standard Lactobacillus gasseri strain ATCC 33323. Conclusion: By screening 166 strains of Lactobacillus gasseri， 61 strains were demonstrated， approximately 36.75%， possessed steady and significant lipid-lowing activities. Among them， Lactobacillus gasseri BDUP strain exhibited the strongest effect to reduce lipid accumulation in HepG2 cells and hyperlipidemic mice， showing a favorable role in mitigating hyperlipidemia.