  Effects of disorder on electron-doped iron pnictides are investigated
systematically based on self-consistent Bogoliubov-de Gennes equations.
Multiply impurities with same scattering potential (SP) are randomly
distributed in a square lattice. Probability distribution functions of
normalized order parameters for different impurity concentrations
$\delta_{imp}$, different electron doping concentrations $\delta$ are
investigated for given SPs. Samples are found to be very robust against weak
SP, in which order parameters do not have qualitative change even at very large
$\delta_{imp}$. While strong SP is able to easily break down the order
parameters. For moderate SP, variations of order parameters on and around
impurities strongly depend on $\delta$, however the distribution functions of
normalized order parameters have similar behavior as $\delta_{imp}$ increases.
Compared with superconducting (SC) order, the magnetic order is more sensitive
to multi-impurity effect. The spatial spin density wave pattern has already
been destroyed before the system loses its superconductivity. Dependence of SC
order on temperature is similar to that of impurity-free case, with the
critical temperature being remarkably suppressed for high $\delta_{imp}$.
