Objective To investigate the effects and mechanism of lycopene on the proliferation and apoptosis of human hepatoma cell HepG2.Methods The human HepG2 cells in logarithmic growth phase were treated with lycopene (5,10,20 μg/ml) and cisplatin (40 pg/ml).The cellular growth inhibition rate was calculated by methyl thiazolyl tetrazolium (MTT) after 48 h,and cell cycle and apoptosis rate were analyzed by flow cytometry.The expressions of Bax,Bcl-2 and cleaved Caspase-3 proteins were detected by Western blotting.Results After 48 h intervention,the cellular growth inhibition rate of human HepG2 cell in blank control group was 0,and in lycopene (5,10,20 μg/ml) groups and cisplatin group were (21.3 ±4.2)％,(40.5 ±7.6) ％,(63.8 ± 9.1) ％,(37.8 ± 5.9) ％,with significant difference (F =37.905,P =0.000);and compared with blank control group respectively,the differences were statistically significant (t =208.124,P =0.000;t=394.637,P=0.000;t=628.592,P=0.000;t=257.168,P=0.000).The G0-G1 phase rates in lycopene (10,20 pg/ml) groups were (54.0 ± 2.9) ％ and (67.3 ± 3.6) ％,compared with blank control group (37.9± 1.5)％,the differences were statistically significant (t =4.508,P =0.024;t =10.673,P =0.006).The G2-M phase rates in lycopene (10,20 μg/ml) groups were (8.5 ± 0.6)％ and (4.7 ± 0.5)％,compared with blank control group (18.4 ± 0.8) ％,the differences were statistically significant (t =9.975,P =0.008;t =13.864,P =0.003).The apoptosis index (AI) in lycopene (5,10,20 μg/ml) groups and cisplatin group were (19.5 ± 4.8) ％,(43.0 ± 9.2) ％,(67.6 ± 10.1) ％ and (36.9 ± 6.8) ％,compared with blank control group [(3.6 ± 1.7)％],the differences were statistically significant (t =18.617,P =0.001;t =34.295,P =0.000;t =51.437,P =0.000;t =29.804,P =0.000).The expressions of Bcl-2,Bax and the ratio of Bax/Bcl-2 in lycopene (10,20 μg/ml) groups and cisplatin group were 0.42 ± 0.09,0.43 ±0.14,1.02 ±0.39;0.27 ±0.08,0.76 ±0.19,2.81 ±0.85;0.34 ±0.11,0.31 ±0.09,0.91 ±0.40,respectively.Compared with blank control group (0.59 ±0.17,0.18 ±0.06,0.31 ±0.12),the expressions of Bcl-2 were significantly down-regulated,and the differences were statistically significant (t =4.327,P =0.023;t =11.064,P =0.006;t =5.182,P =0.018),the expressions of Bax were significantly upregulated,and the differences were statistically significant (t =9.837,P =0.008;t =17.349,P =0.001;t =10.165,P =0.007),the ratios of Bax/Bcl-2 were significantly increased,and the differences were statistically significant (t=11.521,P=0.006;t=18.194,P=0.001;t=9.537,P=0.008).The expressions of cleaved Caspase-3 protein in lycopene (5,10,20 μg/ml) groups and cisplatin group were 0.25 ± 0.07,0.34 ±0.11,0.46 ± 0.18 and 0.17 ± 0.05,compared with blank control group (0.08 ± 0.03),the differenees were statistically significant (t =8.307,P =0.009;t =13.067,P =0.006;t =16.218,P =0.003;t =5.202,P =0.019).Conclusion Lycopene has inhibitive effect on the growth of human HepG2 cells perhaps through inhibiting proliferation and inducing apoptosis,which may be related to its effects of altering the cell cycle and the expressions of apoptosis-related genes and proteins.