OBJECTIVE： To explore the effect of different doses of Simvastatin on the related indexes of patients with contrast-induced nephropathy （CIN）. METHODS： 168 patients received coronary angiography surgery （CAG） and percutaneous coronary stent implantation （PCI） were randomly divided into control group （42 cases）， low-dose （42 cases）， medium-dose （42 cases） and high-dose groups （42 cases）， all patients were given Lohexol injection 20 ml. 0.9％ Sodium chloride injection was intravenously infused at a rate of 2 ml/（kg·h） 4 h before radiography until the end， then 0.9％ Sodium chloride injection was still intravenously infused at a rate of 2 ml/（kg·h） in the end and 48 h after radiography. 48 h before radiography， low-dose group was orally given Simvastatin tablet 20 mg Medium-dose group was orally given Simvastatin tablet 40 mg. high-dose group was orally given Simvastatin tablet 80 mg， once a day. All patients were treated for 4 d. Kidney function indexes （Scr，Ccr，BUN）， kidney damage indexes （CysC，NGAL， mAlb）， and inflammatory cytokines[（IL）-6，hs-CRP）] before and after radiography， and the incidences of CIN and adverse reactions in all group were observed. RESULTS：After radiography， kidney function indexes， NGAL and mAlb in all group， CysC in control group and low-dose group， CysC after 48 h radiography in medium-dose， high-dose groups were significantly higher than before， while all the indexes after 24 h radiography in medium-dose， high-dose groups were lower than low-dose group and control group， with statistical significances （P＜0.05）； after 48 h radiography， medium-dose， high-dose groups were lower than low-dose group， which was lower than control group， with statistical significances （P＜0.05）. After radiography， the inflammatory cytokines in all groups were significantly higher than before， while medium-dose， high-dose groups were lower than low-dose group， which was lower than control group， with statistical significances （P＜0.05）. The incidence of CIN in medium-dose， high-dose groups were lower than low-dose group， which was lower than control group， with statistical significances （P＜0.05）. The incidence of adverse reactions in high-dose group was higher than medium-dose group， followed by low-dose group and control group， with statistical significances （P＜0.05）. CONCLUSIONS： Both medium-dose and high-dose of Simvastatin can effectively reduce the incidence of CIN， improve kidney functions， and reduce kidney damage indexes and inflammatory cytokine levels， while the safety of medium-dose is superior to high-dose.