  Recent high-energy cosmic $e^\pm$ measurement from the DArk Matter Particle
Explorer (DAMPE) satellite confirms the deviation of total cosmic ray electron
spectrum above 700-900 GeV from a simple power law. In this paper we
demonstrate that the cascade decay of dark matter (DM) can account for DAMPE's
TeV $e^+e^-$ spectrum. We select the least constraint DM decay channel into
four muons as the benchmark scenario, and perform an analysis with propagation
variance in both DM signal and the Milky Way's electron background. The
best-fit of the model is obtained for joint DAMPE, Fermi-Large Area Telescope
(Fermi-LAT), High Energy Stereoscopic System (HESS), high energy electron data
sets, and with an $\mathcal{O}(10^{26})$ second decay lifetime, which is
consistent with existing gamma ray and cosmic microwave background limits. We
compare the spectral difference between the cascade decay of typical
final-state channels. The least constrained $4\mu$ channels give good fits to
the electron spectrum's TeV scale down-turn, yet their low energy spectrum has
tension with sub-TeV positron data from AMS02. We also consider a three-step
cascade decay into eight muons, and also a gamma-ray constrained $4\mu,4b$
mixed channel, to demonstrate that a further softened cascade decay signal
would be required for the agreement with all the data sets.
