Solid-liquid equilibrium data are the basis of extraction processes. Traditional wet residue method is known as the most commonly used technique for analyzing equilibrium data for ternary solid-liquid systems. However, when the solid phase contains more than two substances, the wet residue method is restricted. Aiming at this problem, we proposed a novel quasi-ternary wet residue approach that is specialized for analyzing the composition of solid phase for quaternary and more complex systems. To evaluate the applicability of the proposed technique, case studies were introduced in this paper: For a quaternary water-sugar system composed of D-glucose, D-xylose, L-arabinose and H2O, experimentally obtained solid-liquid equilibrium data were utilized to determine the composition of pure solid phase at different temperatures and; For two quaternary water-salt systems, i.e., NaCl-KCl-MgCl2-H2O and NaCl-CaCl2-MgC12-H2O, compositions of solid phase were methodologically analyzed, respectively. The results allow for effective investigating relations of solid-liquid phase equilibria for quaternary and more complex systems via the proposed technique. (C) 2017 Published by Elsevier B.V.