<p>The study of dissolution thermodynamics of Li₃PO₄ in Li–Na–K–B–Cl–S system is of significance to direct prepare Li₃PO₄ with phosphates which avoids concentrating the LiCl brine. The solubility of Li₃PO₄ was determined in the Li–Na–K–B–Cl–S system and LiCl brine within the temperature range of 291.15 to 363.15&#xa0;K. The results indicate that the solubility of Li₃PO₄ in Li–Na–K–B–Cl–S is related to temperature and impurities, decreasing with increasing temperature. Small amounts of Na₂B₄O₇ show the most significant improvement in the solubility of Li₃PO₄, followed by Na₂SO₄. The ion association structure plays a crucial role in reducing the solubility of Li₃PO₄ as the concentration of NaCl or KCl increases. The common ion effect of added LiCl on the reduction of Li₃PO₄ solubility is more significant than the salting-out effect of added NaCl or KCl. Furthermore, the Van’t Hoff, Modified Apelblat, and Quadratic Polynomials models were used to fit solubility, where the Quadratic Polynomials model performs best. The maximum values of the relative deviation (<i>RD</i>), relative mean deviation (<i>RAD</i>) and root mean square deviation (<i>RMSD</i>) were 1.71%, 6.58 × 10⁻³, and 4.22 × 10⁻⁵. Moreover, apparent thermodynamic parameter analysis indicated that the dissolution of Li₃PO₄ in Li–Na–K–B–Cl–S systems is unfavorable to exothermal and exentropic. This process is non-spontaneous, primarily driven by entropy. The salt solution exhibits a non-linear enthalpy-entropy compensation relationship, and the driving forces varies with the content of components. This study will provide thermodynamic basis for crystallization process of Li₃PO₄ from Dong-Taijinaier Salt Lake in the industrial production process.</p>