This experiment was conducted to establish an efficient culture method for bovine mammary epithelial cells (bMEC) in vitro,a nd to research the effect of different concentrations (0, 0.1, 10 and 100ng/mL) insulin-like growth factor-I (IGF-1) on the mRNA expression of genes related to milk protein and fat synthesis in bMEC. Bovine mammary epithelial cells were cultured by tissue mass culture method, and cells were purified according to different sensitivity to trypsin of fibroblasts and bovine mammary epithelial cells. The growth curve of purified cells was detected by cell counting assay method. The expression of keratin 18 was detected by immunofluorescent histochemistry staining method. mRNA expression of 8 genes were measured by real time quantified PCR(RT-qPCR).The results showed that mRNA abundance of insulin-like growth factor-I receptor (IGFIR), insulin-like binding protein 3 (IGFBP3), α_S1-casein (CSN1S1) and κ-casein (CSN3) did not differ (P > 0.05) within different concentrations of IGF-1. However, within the increasing concentrations of IGF-1, the mRNA abundance of β-casein (CSN2), acetyl-CoA carboxylase (ACACA), fatty acid synthase (FASN) and fatty acid binding protein 3 (FABP3) increased significantly (P < 0.05). These results indicated that IGF-1, as an important cytokine, might involve in regulating the mRNA expression of genes related to milk protein and fat synthesis in bovine mammary epithelial cells in vitro.