Phase equilibrium of ternary Ga-Sb-Zn system was investigated by applying CALPHAD method and using literature thermodynamic data for constitutive binary systems. The liquidus surface and isothermal section at 673 K were calculated. Calculated results were verified experimentally on the alloys samples with the compositions corresponding to the characteristic vertical sections: SbZn (1:1)-Ga; GaZn(1:1)-Sb; and GaSb(1:1)-Zn. Phase transitions temperatures were determined by differential thermal analysis and differential scanning calorimetry. Microstructure and phase composition investigation were investigated by using scanning electronic microscopy with energy dispersive spectrometry. The experimental and analytical results showed good agreement, concerning the temperatures of phase transitions and phase compositions of alloys concerned.