An active ultrafast formation and modulation of dual-band plasmon-induced transparency[PIT]effect is theoretically and experimentally studied in a novel metaphotonic device operating in the terahertz regime,for the first time,to the best of our knowledge.Specifically,we designed and fabricated a triatomic metamaterial hybridized with silicon islands following a newly proposed modulating mechanism.In this mechanism,a localized surface plasmon resonance is induced by the broken symmetry of a C2 structure,acting as the quasi-dark mode.Excited by exterior laser pumps,the photo-induced carriers in silicon promote the quasi-dark mode,which shields the near-field coupling between the dark mode and bright mode sup-ported by the triatomic metamaterial,leading to the dynamical modulation of terahertz waves from individual-band into dual-band PIT effects,with a decay constant of 493 ps.Moreover,a remarkable slow light effect occurs in the modulating process,accompanied by the dual-transparent windows.The dynamical switching technique of the dual-band PIT effect introduced in this work highlights the potential usefulness of this metaphotonic device in optical information processing and communication,including multi-frequency filtering,tunable sensors,and optical storage.