1 approximately 3 days old Piglet's primary preadipocytes in vitro were cultured and treated with 0micromol/L (control group), 10microlmol/L (lower dose group), 20micromol/L(middle dose group) and 50micromol/L, 100micromol/L (higher dose group) RES. Cell proliferation and viability were analyzed by MTT assay. The degree of differentiation and adipogenesis were measured by Oil Red O staining extraction assay and the expression of Sirt1 (sirtuin) mRNA were detected by RT-PCR. The results showed the optical density (OD) of MTT and Oil Red O staining were all decreased, especially treated by 50micromol/L, 100micromol/L RES at 72h and 96h (P < 0.01); the ratio of OD of the expression of Sirt1 mRNA to that of beta-actin mRNA were increased after treated by 100micromol/L RES (P < 0.01). RES can inhibit proliferation and differentiation of pig preadipocytes in certain degree. Higher dose of RES can markedly decrease adipogenesis and prevent preadipocytes differentiation into adipocytes, which may be in part associated with its effect on increasing the expression of Sirt1 mRNA.