Objective To clarify the role of mitochondrial division mediated by sterol O⁃acyltransferase 1 （SOAT1）in vascular calcification（VC）. Methods Mouse vascular smooth muscle cells（VSMCs）were divided into four groups：si⁃NC + Con（SOAT1 negative control siRNA transfected into VSMCs），si⁃NC + β⁃GP（SOAT1 negative control siRNA transfected into VSMCs），si⁃SOAT1 + Con（SOAT1 siRNA transfected into VSMCs）and Si⁃SOAT1 + β. CCK⁃8，wound healing test and alizarin red staining were performed to evaluate the proliferation， migration and osteogenic differentiation of VSMCs. The mitochondrial morphology and oxidative stress level of VSMCs were analyzed. Twenty C57BL/J mice were randomly divided into four different groups，with 5 mice in each group：control group（Ctrl group），5/6 nephrectomy plus phosphate diet treatment group（NTP group），NTP + si⁃NC group and NTP + si⁃SOAT1 group. The expression of RUNX2，SOAT1 and α⁃SMA in mouse aorta was analyzed by immunofluorescence. Results In different time periods（0，1，3，5，7 and 14 d）of β⁃GP culturation，the protein level of osteogenic markers RUNX2 and SOAT1 in VSMCs gradually increased in a time ⁃dependent manner（P < 0.05），and the contraction marker α⁃ SMA in VSMCs gradually decreased in a time ⁃ dependent manner（P < 0.05）. Compared with those in si⁃NC + Con group，the cell proliferation rate，the ratio of EdU positive cells，cell migration and alizarin red staining intensity increased significantly in si⁃NC + β⁃GP group（P < 0.05）. Compared with those in si⁃NC + β⁃GP group，the cell proliferation rate，EdU positive cell ratio，cell migration and alizarin red staining intensity decreased significantly in si⁃SOAT1 + β⁃GP group（P < 0.05）. The protein level of RUNX2 and SOAT1 in si⁃SOAT1 + β⁃GP group were significantly lower than that in si⁃NC + β⁃GP group（P < 0.05），and the protein level of α⁃SMA was higher than that in si⁃NC + β⁃GP group（P < 0.05）. Compared with those in si⁃NC + Con group， the mitochondrion breakage and ROS level produced by mitochondria increased significantly in si ⁃ NC + β ⁃ GP group（P < 0.05）. Compared with those in si⁃NC + β⁃GP group，the mitochondrion breakage and ROS level produced by mitochondrion decreased significantly in si⁃SOAT1 + β⁃GP group（P < 0.05）. Compared with those in Ctrl group， the positive area of alizarin red staining and the expression of RUNX2 and SOAT1 protein in aorta in NTP group and NTP + si⁃NC group increased significantly（P < 0.05）. Compared with those in NTP + si⁃NC group，the posi⁃ tive area of alizarin red staining and the expression of RUNX2 and SOAT1 protein in aorta decreased significantly in NTP + si ⁃SOAT1 group（P < 0.05）. Conclusion High concentration of phosphate exposure can induce VC， which may be related to mitochondrial division mediated by SOAT1.