The aim of this work is to investigate improving the effects for adding ionic liquids (ILs) to the working fluids of absorption cycle, lithium bromide aqueous solution (H2O + LiBr), and lithium chloride aqueous solution (H2O + LiCl). 1,3-Dimethylimidazolium chloride ([Dmim]Cl) and 1,3-dimethylimidazolium tetrafluoroborate ([Dmim]BF4) were selected to be additives. The vapor pressure data were measured for the H2O + LiBr + [Dmim]Cl system (LiBr/[Dmim]Cl mass ratio = 3), H2O + LiBr + [Dmim]BF4 system (LiBr/[Dmim]BF4 mass ratio = 2), H2O + LiCl + [Dmim]Cl system (LiCl/[Dmim]Cl mass ratio = 2), and H2O + LiCl + [Dmim]BF4 system (LiCl/[Dmim]BF4 mass ratio = 2) by means of the boiling point method, at temperatures from (303.60 to 439.42) K and the mass fraction of absorbent species from 0.20 to 0.70, respectively. The Antoine-type equation was used to correlate the experimental data of the ternary systems, and the agreements with the experimental data were excellent; that is, the average absolute relative deviations (ARDs) for pressure between experimental and calculated values were 1.05 %, 0.75 %, 0.63 %, and 0.92 % for the systems. Compared with traditional working fluids of absorption cycle, H2O + LiBr and H2O + LiCl, the promising results show that four ternary systems investigated in this work might be used as alternative working fluids to improve the performances of absorption cycles and liquid desiccant dehumidification systems.