In this study, an animal model of obese mice was established by high-fat diet induction, and different doses of carnosic acid (50 or 100 mg/kg•bw) were used to intervene in mice on high-fat diet. After the intervention, the obesity indexes and body weights of mice in different groups were compared. Real-time fluorescence quantitative PCR was used to detect and analyze the liver and epididymal adipose tissue, and the differences in the expression levels of lipid metabolism-related genes in mice of different groups were compared. The results showed that the obesity rate of high-fat diet mice exceeded 20%. Carnosic acid could ameliorate the weight gain of high-fat diet mice and regulate the expression of lipid synthesis- and metabolism-related genes. Carnosic acid intervention could down-regulate the expression levels of PPAR-γ and FASN genes in the liver and epididymal adipose tissues of obese mice (P<0.05), whileup-regulating the expression levels of lipid decomposition-related genes. Among which, the relative expression levels of PPAR-α, HSL and CPT-1 genes in the liver of the mice in the high-dose carnosic acid intervention group were 2.36 times, 2.26 times and 1.47 times those of the highfat group, respectively. The intervention of carnosic acid could down-regulate the expression levels of the PPAR-γ and FASN genes in the liver of obese mice, as well as the expression levels of the PPAR-γ, FASN and SCD-1 genes in the epididymal adipose tissues, thereby inhibiting the differentiation of adipocytes and reduces the rate of adipogenesis. The intervention of carnosic acid could also up-regulate the expression levels of the PPAR-α, HSL and CPT-1 genes in the liver of obese mice, and the expression level of the HSL gene in the epididymal adipose tissues, thereby promoting triglyceride hydrolysis and mitochondrial thermogenesis, accelerating the oxidative decomposition of fat, and eventually inhibiting the accumulation of fat in the liver and adipose tissues. The above results indicate that the intervention of carnosic acid can ameliorate obesity by regulating the expression of genes related to lipid synthesis and decomposition.