Objective：To investigate the combined effect of CdCl2 and nicotine on the cell cycle and apoptosis of mouse spermatogonium(GC-1).Methods：CCK-8 assay was used to detect the inhibition of GC-1 cell proliferation in the CdCl2 groups, the nicotine groups, and the combined groups at 24 hours. Flow cytometry was used to detect the effects of the CdCl2 groups, the nicotine groups, and the combined groups at 24 hours on the cell cycle and apoptosis of GC-1 cells. Results：The inhibitory effect on the proliferation of GC-1 cells was increased with the rise of CdCl2 and nicotine concentrations , the IC50 values of CdCl2 and nicotine alone was 5.409μmol/L, 2814μmol/L. When CdCl2 and nicotine were used in combination, the IC50 value of GC-1 cells was 4.422 μmol/L for 0.175 mmol/L nicotine, 4.532 μmol/L for 0.35 mmol/L nicotine, 3.309 μmol/L for 0.7 mmol/L nicotine, and 2.532 μmol/L for 1.4 mmol/L nicotine ,all of which were lower than that of the groups in which CdCl2 was used alone. The combination of CdCl2 and nicotine had a synergistic effect. At a CdCl2 concentration of 2.5 μmol/L, the IC50 concentration of the combination group was lower than that of nicotine alone. The results showed that percentage of G0/G1 phase cells was decreased in the 2.5 μmol/L CdCl2 group and 1.4 mmol/L nicotine group; compared with the CdCl2 groups and the nicotine groups, percentage of G0/G1 phase cells was decreased in the CdCl2 and nicotine combination groups; percentage of G2/M phase cells was increased in the 2.5 μmol/L CdCl2 group, and compared with the CdCl2 groups and nicotine groups, the cells were blocked in G2/M phase in the combined groups. Combined effects of CdCl2 and nicotine on the cell cycle had a synergistic effect , and the effect of CdCl2 on the synergistic effect was stronger. Proportion of cell apoptosis was increased in 2.5μmol/L CdCl2 group. Compared with the CdCl2 groups and the nicotine groups, percentage of cell apoptosis in the CdCl2 and nicotine combined groups were increased significantly, and the effect of CdCl2 was stronger for the synergistic effect. Conclusion：Combination of CdCl2 and nicotine had a synergistic effect on mouse spermatogonium(GC-1) which could lead to enhanced cytotoxicity, G2/M cell cycle arrests, and cell apoptosis. And CdCl2 was the main effect factor of synergistic effect.