Abstract: Objective To study the effects and mechanism of resveratrol(Res) on apoptosis and cell cycle in 3T3-L1 preadipocytes. Methods 3T3-L1 preadipocytes were treated with different doses of Restreatment (0,25,50,75,and 100μmol/L, 0μmol/Las the negative control) for 24, 48 or 72h. The Fluorescence microscope, MTT assay,and flow-cytometry were used for measuring cell morphology, cell proliferation, cell cycle, and apoptosis. Results After treated with 50μmol/L of Res for 48h, 3T3-L1 preadipocytes exhibited typical apoptosis features when observed under fluorescence microscope. MTT assay showed that, after different doses of Res treatment (0, 25, 50, 75, and 100μmol/L) for 24h, cell proliferation rate was 100%, (97.00 ±1.00)%, (91.00 ±2.65)%, (90.67 ±2.52)%, and (86.00±3.61)%, respectively; after the similar Res treatment for 48h, cell proliferation rate was 100%, (86.67±2.52)%, (76.00±2.00)%, (34.33±2.08)%, and(30.33±2.52)%, respectively; also, after the similar Res treatment for 72 h, cell proliferation rate was 100%, (82.00±2.65)%, (65.67±3.06)%, (21.00±3.61)%, and (16.33±3.21)%, respectively. Partial correlation analysis showed a negative correlation between cell proliferation rate and intervention time, concentration of Res (r=-0.72?-0.83, all P<0.01). After different doses of Res treatment (0, 25, 50, 75, and 100μmol/L) for 24h, the portion of cells in G0/G1 phase was (27.23±2.63)%, (39.03±2.74)%, (80.20±5.15)%, (87.97±3.12)%, (90.80±2.08)%, respectively; as the same, the portion of cells In S phase was (72.43±2.99)%, (63.93±6.90)%, (19.80±5.15)%, (12.20±2.86)%, (9.20±2.08)%, respectively. From the results of the cell cycle examination, the portion of cells in G0/G1 phase decreased (P<0.05orP <0.01) and increased evidently in S phase (P<0.05 or P < 0.01) in a dose dependent manner. After different doses of Res treatment (0, 25, 50, 75, 100μmol/L) for 48h, apoptosis rate was (2.90±0.10)%, (5.40±3.81)%, (8.23±4.24)%, (29.77±6.18)%, (27.23±3.17)%, respectively; as the same, necrosis rate was (7.50±0.87)%, (12.00±4.89)%, (12.27±3.81)%, (12.67±6.13)%, (20.73±2.64)%, respectively. The apoptosis and necrosis of 3T3-L1 preadipocytes were statistically significant different between 100μmol/L Res group and negative control group (P<0.05 or P<0.01). Conclusion At a certain dose range (0-100μmol/L), Res may inhibit the life cycle and promote apoptosis of 3T3-L1 preadipocytes.