Liquid-liquid equilibrium (LLE) for the ternary system of 3-mercaptopropionic acid (3-MPA) + water + trichloromethane (TCM) was measured at temperatures of (303.2, 313.2, and 323.15) K under atmospheric pressure, and the corresponding phase diagrams were illustrated. Moreover, it was demonstrated that the presence of NaCl in the system can promote the separation of the two liquid phases, which favors the extraction of 3-MPA from water by TCM. The experimental data were correlated by using the nonrandom two-liquid (NRTL) equation, which showed that the calculated data are in good agreement with the experimental data, and the NRTL model can accurately predict the LLE of the ternary system at specific temperatures using the obtained interaction energy parameters.