By means of tensile testing machine,metalloscope and equal channel angular extrusion（ECAE） testing,preparation of Mg-Al magnesium alloy semi-solid billets and its thixo-extrusion forming were investigated.The results show that desirable strain induced effects can be obtained by ECAE.After Mg-Al magnesium alloy was processed by ECAE,mechanical properties was increased with the refinement of grain size.Semi-solid billets prepared by new SIMA were characterized by fine grains,desirable spheroidization and homogeneous microstructure.In contrast,semi-solid billets prepared by direct isothermal treatment were characterized by coarse grain and terrible spheroidization.High mechanical properties and fine grains occur in angle frame components manufacture by thixo-extruding new SIMA prepared Mg-Al series semi-solid billets including AZ61,AZ80,AZ91D and AM60.Tensile strengthes of angle frame components reach 306.8,308.3,299.8 and 321.6MPa,respectively,and elongations are 21.6%,28.4%,14.6% and 29.6%,respectively.