A family of new ether-functionalized ILs based on trialkylimidazolium cations with one or two ether groups and TFSA(-) anion was synthesized and characterized. Their properties including melting point, thermal stability, viscosity, conductivity, and electrochemical windows were determined and compared to those of the trialkylimidazolium ILs without ether group. The relationship between the cations structure and IL physicochemical properties was systematically studied. Most of these ether-fiinctionalized ILs were liquids at room temperature, and the melting points of 21 ILs were lower than -60 degrees C. At room temperature, 26 ILs owned the viscosities lower than 100 mPa s, and the viscosities of IM(2o1)12TFSA and IM(2o2)12TFSA were 57.4 and 54.4 mPa s.