Aim To explore the effect and mechanism of acid environment on media vascular calcification of chronic renal failure rats. Methods In vivo experiment:healthy male SD rats were randomly divided into control group, renal failure group, vascular calcification group and acid intervention group, calcification was measured by Alizarin red staining and enzyme linked immunosorbent assay. In vitro experiment:vascular smooth muscle cells (VSMC) were primarily cultured in vitro and randomly divided into control group, high phosphorus group, acid intervention group and inhibitor group, calcium deposition and ALP activity were measured by Alizarin red staining, quantification of calcium and enzyme linked immunosorbent assay, the expression of BMP-2, Smad1 and Runx2 was detected by RT-PCR and Western blot. Results In vivo experiment:the vascular calcification model of rats with chronic renal failure was successfully prepared. Compared with vascular calcification group, calcium deposition in acid intervention group decreased (P＜0.05).In vitro experiment:compared with control group, calcium deposition, alkaline phosphatase (ALP) activity and the expression of Runx2 in high phosphorus group increased (P＜0.05). Compared with high phosphorus group, calcium deposition, ALP activity and the expression of Runx-2, BMP-2 and Smad1 in acid intervention group decreased (P＜0.05). Compared with high phosphorus group, calcium deposition and the expression of Runx2 in inhibitor group also decreased (P＜0.05). Conclusions Acid environment can inhibit the occurrence of vascular calcification in chronic renal failure rats, the mechanism was presumably that vascular smooth muscle cells osteogenesis/chondrogenesis-like phenotypic transformation was inhibited by BMP-2 signaling pathway.