Abstract: Room temperature ionic liquids (RTILs) with various anions and cations were synthesized. The effects of the structure of RTILs and reaction conditions on the isomerization of npentane were investigated. The mole ratio of AlCl3 to Et3NHCl plays an important role in the acidity and the catalysis of the RTILs. Normal butyl alcohol was selected as the initiator of the isomerization of npentane and its dosage is about 2.5 weight percent of the npentane. The optimal reaction temperature, reaction time and stir speed are 30℃, 10h and 1500r/min, respectively. Under these conditions, the conversion and the isomerization ratio are 85.66% and 92.86%, respectively.