Lard and corn oil were used to explore the difference of obesity in BALB/c mice caused by oil and fat. And the effects of Lactobacillus rhamnosus ATCC 53103 (LGG) on prevention of obesity and regulation of mice intestinal flora were analyzed. A total of 50 5-week-old BALB/c male mice were randomly divided into 5 groups included control check (CT)， high-lard fed group (S)， high-corn oil fed group (P)， high-lard fed + LGG gavage group (SL) and high-corn oil fed + LGG gavage group(PL). The experiment lasted for 8 weeks and the related indexes were detected. The results showed that obesity was much easier to be caused by excessive lard compared with excessive corn oil. The body weight (41.42±2.30) g， body mass index (BMI， 4.24 kg/m2±0.26 kg/m2)， Lee's index (351.44±9.06)， fat coefficient (118.87±3.91) mg/g， total triglyceride (TG， 0.81 mmol/L±0.08 mmol/L)， low density lipoprotein cholesterol (LDL-C， 0.29 mmol/L±0.01 mmol/L)， alanine aminotransferase (ALT， 53.42 U/L±0.95 U/L) and aspartate aminotransferase (AST， 164.65 U/L±9.35 U/L) were all significantly higher in mice in group S than in group P while only the liver index was higher in mice in group P(51.07±1.35) mg/g than in group S (47.32 mg/g±1.93 mg/g， P<0.05). Amongst the changed intestinal flora in mice， the relative abundance of Bacteroidetes (8.69±4.68)% and CF231 (0.31±0.19)% decreased while Allobaculum (2.19±1.47)% increased in group S. And the F/B ratio was higher in group S (9.15±1.19) than that in group P (4.25±0.57， P<0.05). Comparatively， only the relative abundance of Streptococcus was slightly higher in mice in group P (14.41±6.37)% than in group S (4.91±2.23)%. However， LGG intervention was more effective in preventing obesity and regulating intestinal flora disorder in mice caused by lard. The body weight and fat coefficient of mice were lower in group SL (34.53 g±1.53 g， 26.10 mg/g±2.51 mg/g) compared with in group PL (37.69 g±2.41 g， 65.88 mg/g±1.98 mg/g， P<0.05). And the up-regulation of Bacteroides was more obviously in group SL. The down-regulation of Firmicutes was observed， but the regulation of Deferribacteres could not be conducted by LGG in group PL (P>0.05). In conclusion， obesity was more likely to be caused by lard than by corn oil. But LGG was more effectively in preventing obesity and regulating intestinal flora disorder caused by lard.