Tensile　properties　of　ultrafine　grain　5052　aluminum　alloy　processed　by　repetitive　groove　pressing,　using　a　novel　self-designed　groove　pressing　die,　were　investigated.　The　results　show　that　both　constrained　groove　pressing　(CGP)　and　unconstrained　groove　pressing　(UGP)　are　both　good　for　strengthening　the　5052　aluminum　alloy,　and　the　ultimate　tensile　strength　increases　with　the　increasing　of　pass　number.　Fracture　surface　morphology　demonstrates　that　the　fracture　mode　is　ductile.　The　elongation　of　the　sample　processed　by　CGP　keeps　constant　approximately,　and　increases　slightly　after　the　third　pass.　But　the　elongation　of　the　UGP　processed　sheets　decreases　continually　with　the　increasing　of　pass　number,　and　much　lower　than　that　of　the　CGP.　The　differences　in　tensile　properties　of　the　CGP　and　UGP　processed　ultrafine　grain　5052　aluminum　alloy　are　essentially　attributed　to　the　difference　in　grain　refinement　by　CGP　and　UGP.　Compared　with　UGP,　CGP　processed　sheets　exhibit　better　comprehensive　mechanical　properties.