[en] The subsolidus phase relationships of ternary system Na₂O-ZnO-WO₃ have been investigated by X-ray diffraction (XRD) and differential thermal analyzer (DTA). All the samples were synthesized in the temperature range from 530 to 850 deg. C in air. There are one ternary compound and five binary compounds in the Na₂O-ZnO-WO₃ system, which can be divided into eight three-phase regions. The crystal structure of the ternary compound Na_3.6Zn_1.2(WO₄)₃ is determined by single-crystal structure analysis method. It belongs to triclinic system with space group P1-bar and lattice constants a = 7.237 (5) A, b = 9.172 (6) A, c = 9.339 (6) A and α = 94.920 (4)^o, β = 105.772 (9)^o, γ = 103.531 (8)^o, Z = 2. DTA analyses indicate that the compound Na₂WO₄ is not suitable to be the flux for ZnO crystal growth below 1250 deg. C, since no liquidus was observed in the system before 1250 deg. C