Optical　excitation　of　metallic　nanostructures　induces　strong　intraband　transitions,　leaving　transient　depletion　below　the　Fermi　level,　which　allows　transient　interband　transition　to　this　depletion　band.　This　is　equivalent　to　the　lowering　of　the　threshold　for　interband　transitions　and　pushes　the　plasmonic　band　to　the　red.　As　a　result,　localized　surface　plasmon　resonance　(LSPR)　is　＂extinguished＂　or　＂quenched＂　around　the　bandedge,　in　contrast,　the　interband　optical　absorption　becomes　enhanced　and　redshifted.　The　corresponding　transient　absorption　(TA)　signals　have　equal　lifetimes　and　opposite　signs.　Moreover,　the　TA　spectrum　is　found　to　be　a　secondorder　differential　of　the　steady-state　optical　extinction　spectrum　over　the　studied　band.　This　is　a　commonly　existing　mechanism　for　metallic　nanostructures　and　verified　with　gold　in　this　work.　Such　a　discovery　is　completely　different　from　the　optical-excitation-induced　redshift　of　LSPR　through　enhanced　electronic　scattering　and　is　important　for　understanding　the　ultrafast　spectroscopic　response　of　plasmonic　nanostructures　with　clear　photophysical　insights,　supplying　solid　basis　for　exploring　optical　logic　device　and　optical　data　processing　techniques.