Industrial organo-sulfonic acid wastewater contains high concentrations of inorganic salts and various organo-sulfonates, causing significant challenges for their efficient removal, separation, and recovery. These waste streams often arise from complex industrial processes, and their intricate compositions make effective treatment and recycling more difficult. Herein, the phase equilibrium data for the sodium benzenesulfonate (BSNa)-sodium sulfate (Na2SO4)-water (H2O) ternary system were measured at temperatures of 273.15, 283.15, and 313.15 K using both the isothermal dissolution equilibrium method and Schreinemakers' wet residue method. Thermodynamic analysis of the dissolution process was performed using the van't Hoff equation, offering valuable insights into the system's behavior under different temperature conditions. At 313.15 K, the phase diagram indicated one invariant point, two univariant curves, and three distinct crystallization regions, corresponding to Na2SO4, BSNa, and their co-crystal mixture. However, at the lower temperatures of 273.15 and 283.15 K, the system displayed only one invariant point, one univariant curve, and two crystallization regions, specifically for Na2SO4?10H2O and a co-crystal region consisting of Na2SO4?10H2O and BSNa. Notably, no distinct crystallization region or solubility curve for BSNa was observed at these lower temperature ranges. Additionally, freeze crystallization experiments demonstrated no evidence of double salts or eutectic mixtures forming within the ternary system. This suggested that separating the components at lower temperatures, particularly around 283.15 K, was not only more efficient but also more cost-effective for obtaining pure salts. The thermodynamic analysis further revealed that the dissolution of Na2SO4 in this system was an endothermic, non-spontaneous process with an increase in entropy. The changes in enthalpy significantly influence the Gibbs free energy of dissolution, impacting the separation process. This research provided insight into the effective separation and recovery of BSNa and Na2SO4 from industrial wastewater, offering a solid foundation and practical guidance for improving wastewater treatment processes in industrial applications.