  In this work, we explore the potential of probing the inelastic dark matter
(DM) model with an extra U(1)D gauge symmetry at the Large Hadron Collider,
ForwArd Search ExpeRiment and Super Tau Charm Factory. To saturate the observed
DM relic density, the mass splitting between two light dark states has to be
small enough, and thus leads to some distinctive signatures at these colliders.
By searching for the long-lived particle, the displaced muon-jets, the soft
leptons, and the mono-photon events, we find that the inelastic DM mass in the
range of 1 MeV to 210 GeV could be tested.
