Hydrate-based gas separation (HBGS) technology can effectively separate CH4 and CO2 in multicomponent gases. To provide the necessary basic data for the HBGS technology, the hydrate phase equilibrium conditions of a ternary gas mixture (CH4/CO2/N-2 = 0.5/0.4/0.1) were determined and compared in tetrabutylammonium bromide (TBAB) aqueous solutions with different mass fractions (0.05, 0.1, 0.2, and 0.4). The results indicated that all four concentrations of TBAB aqueous solution could shift the hydrate phase equilibrium conditions of the ternary gas mixture to higher temperatures and lower pressures; this influence was enhanced with higher TBAB concentrations. When the TBAB mass fraction was 0.4, under the same phase equilibrium pressure conditions, the phase equilibrium temperature increased by a range of approximately 9-14 K compared with that of a pure water system. Meanwhile, TBAB had a greater impact on the phase equilibrium conditions of hydrates containing larger proportions of CO2 and CH4 gas and a greater impact on the phase equilibrium conditions of CO2 and CH4 gas hydrates than on N-2 hydrate.