  With experimental results of AMS on the spectra of cosmic ray (CR) $e^{-}$,
$e^{+}$, $e^{-}+e^{+}$ and positron fraction, as well as new measurements of CR
$e^{-}+e^{+}$ flux by HESS, one can better understand the CR lepton ($e^{-}$
and $e^{+}$) spectra and the puzzling electron-positron excess above $\sim$10
GeV. In this article, spectra of CR $e^{-}$ and $e^{+}$ are fitted with a
physically motivated simple model, and their injection spectra are obtained
with a one-dimensional propagation model including the diffusion and energy
loss processes. Our results show that the electron-positron excess can be
attributed to uniformly distributed sources that continuously inject into the
galactic disk electron-positron with a power-law spectrum cutting off near 1
TeV and a triple power-law model is needed to fit the primary CR electron
spectrum. The lower energy spectral break can be attributed to propagation
effects giving rise to a broken power-law injection spectrum of primary CR
electrons with a spectral hardening above $\sim$40 GeV.
