The solutionized Mg-3.52Sn-3.32Al(wt.%) alloy was processed by equal channel angular pressing (ECAP) via route Bc for 1, 4, and 8 passes, respectively. The microstructure and phase composition of the alloy were analyzed by optical microscope, scanning electron microscopy, transmission electron microscopy and X-ray diffraction, and the room-temperature mechanical properties were measured. The results show that many fine Mg2Sn particles and a few Mg17Al12 phases precipitate in the alloy after ECAP. The mechanical properties of the alloy first increase and then decrease gradually with increasing extrusion passes. The alloy possesses better mechanical properties after ECAP for four passes, the ultimate tensile strength, elongation and hardness increase to 250 MPa, 20.5% and 61.3 HV9.8 respectively, which is increased by 43.7%, 105% and 26.9% compared with the solutionized alloy. The room temperature fractograph of the ECAP processed alloy is ductile-fractured morphology under tensile condition.The mechanical properties of the ECAP processed Mg alloy is dependent on the grain size, precipitate and texture.