Mesoporous molecular sieves MCM-41 was prepared using water-heat synthesis,and the catalyst was loaded with Ni and SiW12 by impregnation.The samples were characterized using XRD and BET surface area and Py-IR.Isomerization of n-heptane over Ni-SiW/MCM-41catalyst was investigated in a continuous flow fixed-bed reactor under atmospheric pressure.The result showed that when Ni content is at 4% and SiW12 content is at 30%,the activity of Ni-SiW12/MCM-41 is best.Isomerization selectivity to iheptane can reach 74% at a higher conversion of n-heptane.