  The null signal from collider and dark matter (DM) direct detector
experiments makes the interaction between DM and visible matter too small to
reproduce the correct relic density for many thermal DM models. The remaining
parameter space indicates that two almost degenerated states in the dark
sector, the inelastic DM scenario, can co-annihilate in the early universe to
produce the correct relic density. Regarding the direct detection of the
inelastic DM scenario, the virialized DM component from the nearby halo is
nonrelativistic and not able to excite the DM ground state, even if the
relevant couplings can be considerable. Thus, a DM with a large mass splitting
can evade traditional virialized DM direct detection. In this study, we connect
the concept of cosmic-ray accelerated DM in our Milky Way and the direct
detection of inelastic scattering in underground detectors to explore spectra
that result from several interaction types of the inelastic DM. We find that
the mass splitting $\delta<\mathcal{O}(1~{\rm MeV})$ can still be reachable for
cosmic ray accelerated DM with mass range $1~{\rm MeV}<m_{\chi_1}<100~{\rm
GeV}$ and sub-GeV light mediator using the latest PandaX-4T data, even though
we conservatively use the astrophysical parameter (effective length) $D_{\rm
eff}=1$ kpc.
