By microwave irradiation, the intermediate compounds of imidazolium ionic liquids, 1-Butyl-3-methylimidazolium bromize([BMIm]Br), 1-propyl-3-methylimidazolium bromize([PMIm]Br), 1-hexyl-3-methylimidazolium bromize ([C6MIm]Br) were synthesized from 1-methylimidazole and organic halide (1-bromopropane,1-bromobutane,1-bromohexane) separately under reflux heating at 80 ℃. Each of them reacted separately with HPF6 for 4 hours at room temperature to get hydrophobic imidazolium ionic liquids:1-butyl-3-methyl-imidazolium hexafluorophosphate([BMIm]PF6) and 1-propyl-3-methyl-imidazolium hexafluorophosphate([PMIm]PF6),1-Hexane-3-methyl-imidazolium hexafluorophosphate([C6MIm]PF6). By measuring the conductivities of these ionic liquids and them in the different solvents, i.e. acetone, carbinol and acetic ether, it was found that the conductivity was affected by the kinds of solvents, temperature, concentration and substituent in imidazole. The longer the chain of the substituent was, the bigger the bulk was and the smaller the conductivity of the ionic liquid was. The higher the temperature or the stronger the concentration was, the bigger the conductivity was.