OBJECTIVE： To study the effects of valsartan on perionstin and AP-1 during renal tubular epithelial cell-mesenchymal tissue （EMT） transformation under the condition of high glucose. METHODS： Human renal tubular epithelial cells （HK-2 cells） were cultured in vitro under the condition of high glucose， and then divided into blank control group， valsartan high-dose， middle-dose and low-dose groups （10－3， 10－4，10－5 mol/L）； normal control group was set up. They were treated for 48 h. The morphology of HK-2 cells was observed； cell viability （OD value） of HK-2 cells were detected， and the content of Ⅲ type collagen， the protein expression of AP-1 and mRNA expression of Periostin and AP-1 were detected. RESULTS： Compared with normal control group， intercellular space of HK-2 cells enlarged and HK-2 cells were separated from nearby cells； exuberant cellular fission， cell viability， the content of Ⅲ type collagen， the protein expression of AP-1， mRNA expression of periostin and AP-1 were strengthened in other group （P＜0.05）. Compared with blank normal group， cell viability， the content of Ⅲ type collagen， the protein expression of AP-1， mRNA expression of periostin and AP-1 were lower in valsartan high-dose， medium-dose and low-dose groups （P＜0.05）， especially in valsartan medium-dose group （P＜0.01）. CONCLUSIONS： High glucose can promote EMT of HK-2 cells. Valsartan can down-regulate the protein expression of Periostin in renal tubular epithelial cell and slow down EMT via inhibiting the expression of AP-1.