A new amino acid ionic liquid (AAIL) based on glutamic acid, 1-butyl-3-methylimidazolium glutamine (BMIGlu), was prepared by Fukumoto's method and characterized by (1)H NMR, differential scanning calorimetry (DSC), and Karl Fischer moisture titration techniques. The density and surface tension of BMIGlu were measured in the temperature range of (308.15 to 343.15) K by the standard addition method (SAM), and then the values of pure BMIGlu were obtained through the linear extrapolation. Furthermore, the volume and surface properties were also discussed.