The　influence　of　Equal　Channel　Angular　Pressing　(ECAP)　deformation　on　the　microstructure　and　magnetic　properties　of　a　semi-magnetic　alloy,　2J4,　was　studied.　In　the　process,　the　sample　is　pressed　from　one　pass　to　the　next　pass　directly　without　rotation.　Results　show　that　the　microstructures　of　2J4　alloy　deformed　by　ECAP　at　room　temperature　are　obviously　refined.　Part　of　original　austenite　transforms　into　martensite,　the　larger　the　deformation,　the　higher　the　transformation　fraction　of　martensite.　The　magnetic　retardation　performance　of　the　specimen　deformed　by　ECAP　is　better　than　that　deformed　by　cold　rolling　with　similar　deformation.　It　has　higher　coercive　force　(Hc),　remanence　(Br)　and　larger　magnetic　energy　(Pro).　ECAP　deformation　is　new　approach　for　fabricating　high　performance　magnetic　materials　with　high　material　utilization　and　low　production　cost.