Plasmonic　nanostructures　have　extensive　applications　in　sensors　and　optoelectronic　devices.　Noble　metals　are　the　most　suitable　candidates　for　the　construction　of　plasmons　due　to　their　high　electrical　conductivity　and　high　plasmonic　activities.　However,　silver　is　easy　to　get　oxidized　and　is　thus　not　suitable　for　plasmonic　nanostructures　with　long-term　stability.　In　contrast,　gold　is　a　most　stable　metal　and　more　extensive　employed　in　plasmon　photonic　structures.　Nevertheless,　plasmon　band　for　gold　starts　from　2.38　eV　to　lower　photon　energies,　ruling　out　the　possible　designs　of　plasmonic　device　in　the　blue　spectrum.　We　solve　this　challenge　by　alloying　gold　and　silver,　which　not　only　overcomes　the　oxidization　problem　of　silver,　but　also　extends　largely　the　plasmonic　band　of　gold　to　the　blue　spectrum.　Using　a　volume　ratio　between　gold　and　silver　of　1:1,　we　achieved　a　blue　shift　of　the　plasmonic　band　edge　to　3.1　eV,　allowing　construction　of　plasmons　in　the　blue　spectral　band.　This　is　found　to　be　based　on　the　realignment　of　the　Fermi　level　between　gold　and　silver　in　the　alloyed　nanoparticles.　Furthermore,　a　practically　applicable　method　is　proposed　here　for　the　fabrication　of　alloyed　plasmonic　nanostructures　of　gold　and　silver,　where　the　thermally　evaporated　bilayers　of　them　are　simply　annealed　into　alloyed　nanoparticles.　The　alloy　ratio　is　controlled　by　the　thickness　of　the　metals,　and　the　quality　of　the　alloyed　nanostructures　may　be　optimized　through　adjusting　the　deposition　sequence　of　these　two　metals　in　the　bilayer.　The　discovered　physics　and　the　fabrication　technique　may　be　extended　to　other　metals　and　are　important　for　plasmonic　photonics.