  We investigate the impact of cosmic filaments on the gas accretion rate,
$\dot{M}_{\rm{gas}}$, of dark matter halos in filaments, based on cosmological
hydrodynamic simulation. We find that for halos less massive than $10^{12.0}\
\rm{M_{\odot}}$, $\dot{M}_{\rm{gas}}$ of halos residing in prominent filaments
(with width $D_{\rm{fil}}>3\ \rm{Mpc}/h$) is lower than halos residing in
tenuous filaments ($D_{\rm{fil}}<3\ \rm{Mpc}/h$) by $20-30\%$ at $z=0.5$, and
by a factor of 2-3 at $z=0$. However, $\dot{M}_{\rm{gas}}$ depends weakly on
the physical distance between halo center and the spine of filaments from high
redshift to $z=0$, only shows clear difference between the inner and outer
regions in prominent filaments at $z=0$. We further probe the thermal
properties of gas in prominent and tenuous filaments, which appear in
relatively highly and intermediate overdense regions, respectively. The gas in
prominent filaments is hotter. Around $26\%$, $38\%$ and $45\%$ of gases in
prominent filaments are hotter than $10^6$ K at $z=1.0, 0.5$ and $z=0.0$
respectively. The corresponding fractions in tenuous filaments are merely $\sim
6\%, 9\%$ and $11\%$. The suppressed gas accretion rate for low-mass halos in
prominent filaments at $z \lesssim 0.5$ may result from the hotter ambient gas,
which could provide a physical processing mechanism to cut down the supply of
gas to halos before they enter clusters. This process meets partially the need
of the preheating mechanism implemented in some semi-analytical models of
galaxy formation, but works only for $\sim 20\%$ of halos at $z < 1$.
