The Mg96Y3Zn1 alloy processed by extrusion and equal channel angular pressing (ECAP) was investigated.It was found that the Mg96Y3Zn1 alloy processed by extrusion and ECAP obtained ultrafine grains and exhibited excellent mechanical properties.After ECAP,the average grain size of Mg96Y3Zn1 alloy was refined to about 400 nm.The highest strengths with yield strength of 381.45 MPa and ultimate tensile strength of 438.33 MPa were obtained after 2 passes at 623 K.The high strength of Mg96Y3Zn1 alloy was due to the strengthening by the grain refimement,the long period stacking (LPS) structure,solid solution,fine Mg24Y5 particles,and nano-scale precipitates.It was found that the elongation was decreased with pass number increasing.It was because that the cracks were preferentially initiated and propagated in the interior of X-phase during the tensile test.