In this paper, a multi-objective optimization of geothermal water desalination plant with ejector refrigeration system is proposed. The multi-objective antlion optimization algorithm is used. Six different optimization scenarios were performed with economic (total investment cost and profit) and thermodynamic (exergy destruction) objectives for refrigerants R11, R114 and R717. Multi-criteria decision making with integrated AHP and PROMETHEE II approach is executed for evaluating the most suitable design project and refrigerant. Besides economic and thermodynamic criteria, three additional environmental criteria were used: ozone depletion potential, global warming potential and toxicity. The sensitivity analysis showed that water desalination plant with R114 refrigerant and coefficient of performance 0.507 is optimal for a wide range of criteria weights. A similar result of the optimal design point is obtained in scenarios where only economic objective functions were considered during the optimization procedure. Furthermore, it is proved that R114 Pareto front is more optimal in comparison with other refrigerants.