Isobaric vapor-liquid equilibrium (VLE) data for (propan-2-ol (1) + water (2) + 1-butyl-3-methylimidazolium tetrafluoroborate(3)) where 3 is an ionic liquid [BMIM](+)[BF(4)](-) at atmospheric pressure (101.32 kPa) were measured with a modified Othmer still. The results showed that the ionic liquid Studied call transfer the azeotropic point and eliminate the azeotropic phenomena when its concentration is Lip to x(3) = 0.20. This means that [BMIM](+)[BF(4)](-) can be used as a promising entrainer in the application of extractive distillation. However, the comparison of the salting-out effect of [BMIM](+)[BF(4)](-) with that of 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM](+)[BF(4)](-) was conducted. The measured ternary data were Correlated using the NRTL equation.