Aim To explore whether warfarin promotes calcification of rat vascular smooth muscle cells (VSMC) through the bone morphogenetic protein (BMP) signaling pathway. Methods Vascular smooth muscle cells were obtained from rat aortic, and identified by immunocytochemistry, then randomly divided into control group, high phosphorus group, warfarin (10 μmol/L) group, warfarin (10 μmol/L)＋vitamin K (10 μmol/L) group. Calcification staining, calcium content and alkaline phosphatase (ALP) activity were measured, the expression of Runx2 protein was detected by Western blot and the expression of BMP-2, Smad1, Runx2 mRNA was detected by RT-PCR. Results The results of alizarin red stain were shown that the number of calcified nodules in the warfarin group was significantly higher than that in the control and high phosphorus group (P＜0.05). The results of calcium content were in line with that of alizarin red stain. The ALP activity in the warfarin group was significantly higher than that in the control and high phosphorus group (P＜0.05). The results of RT-PCR and Western blot were shown that the expression level of Runx2, BMP-2 and Smad1 in the warfarin group was significantly higher than that in the control and high phosphorus group (P＜0.05). However, the calcification content, ALP activity and the expression level of BMP-2, Smad1 and Runx2 in the warfarin＋vitamin K group were significantly lower than those in the warfarin group (P＜0.05). Conclusion The BMP pathway was involved in warfarin-induced vascular calcification of rat vascular smooth muscle cells, which may be achieved by promoting the transdifferentiation of vascular smooth muscle cells.