Zn-5wt.%Al　alloy　was　cast　and　extruded　into　the　tube　in　the　present　work.　The　mechanical　properties　and　degradation　behavior　of　as-cast　and　extruded　alloys　were　investigated.　Compared　with　other　binary　Zn　alloys,　the　extruded　Zn-5wt.%Al　alloy　tube　showed　a　ultra-high　elongation　to　failure　(383.3%)　and　medium　strength　(257　MPa).　The　superplasticity　is　attributed　to　the　grain　boundary　slip　due　to　unique　microstructure,　i.e.　the　ultrafinegrained　alpha-phase　accumulated　mainly　along　the　fine-grained　eta-phase　boundary.　Furthermore,　after　32　days＇　immersion,　the　corrosion　rates　of　as-cast　and　extruded　alloy　were　0.11　mm/y　and　0.15　mm/y,　respectively.　The　electrochemical　polarization　test　and　corrosion　surface　analysis　indicate　an　initial　ultrafine-grained　Al-rich　phase　dissolution　for　extruded　Zn-5wt.%Al　alloy.