• Zn-1.5Mg-0.3Y (wt%) alloy with high strength-ductility and good work-hardening ability was prepared by multi-pass ECAP. • ECAP tailored the size and distribution of microscale and sub-microscale YZn 12 particles. • Homogeneously refined microstructure, and texture deviated from basal plane were beneficial to improvement of ductility. • Twinning in both Zn matrix and refined sub-microscale YZn 12 phase contributed to work hardening ability. In this study, the effects of Y addition on microstructure and mechanical properties of Zn-Mg alloy during multi-pass equal channel angular pressing (ECAP) were systematically investigated. The results show that apart from α-Zn matrix and network-shaped eutectic Zn+Mg 2 Zn 11 structure, micron-sized and submicron-sized YZn 12 particles were formed in as-cast alloy. During multi-pass ECAP, the α-Zn matrix was refined via dynamic recrystallization (DRX), and the eutectic structure was fragmented into fine particles gradually, while the YZn 12 particles became further refined (~100 nm) only from 8p to 12p ECAP. Tensile tests at room temperature indicated that the 12p-ECAP alloy exhibits the optimal mechanical properties with ultimate tensile strength of 465 MPa and fracture elongation of 11%. The fine and uniform microstructure contributes to the enhancement of ductility. Furthermore, the improved work hardening ability of 12p alloy was mainly ascribed from the generation of submicron-sized YZn 12 particles with the size of ~100 nm, which could induce twinning with them and increase the density of geometrically necessary dislocations. The results suggest that the introduction of second phase particles with twinning ability may be effective to improve the work hardening ability of Zn alloys. [ABSTRACT FROM AUTHOR]