An ionic liquid (IL) was prepared by directly mixing InCl3 and 1-methyl-3-butylimidazolium chloride(BMIC) with molar ratio 1:1 under dry argon atmosphere.The densities,and surface tension of pure IL were determined at temperature range of (278.15 to 343.15±0.1K).The properties for ionic liquid based on group Ⅲ were discussed using Glasser's theory.The standard entropy,the surface energy and the crystal energy of ionic liquid were calculated,respectively.The crystal energy of ionic liquid is much lower than ionic solid and this is the underlying reason for forming ionic liquid at room temperature.In addition,a new theoretical model of IL,that is interstice model,was applied to calculate the thermal expansion coefficient of BMIInCl4.The order of magnitude for the thermal expansion coefficient,a,calculated by the theoretical model is in good agreement with experimental value.The result shows that there is much reasonableness for the interstice model of ionic liquid.