  Extinction in ultraviolet is much more significant than in optical or
infrared, which can be very informative to precisely measure the extinction and
understand the dust properties in the low extinction areas. The high Galactic
latitude sky is such an area, important for studying the extragalactic sky and
the universe. Based on the stellar parameters measured by the LAMOST and GALAH
spectroscopy and the ultraviolet photomery by the \emph{GALEX} space telescope,
the extinction of 1,244,504 stars in the \emph{GALEX}/NUV band and 56,123 stars
in the \emph{GALEX}/FUV band are calculated precisely. \textbf{The error of
color excess is 0.009, 0.128 and 0.454 mag for $E_{\rm G_{BP}, G_{RP}}$,
$E_{\rm NUV,G_{BP}}$ and $E_{\rm FUV,G_{BP}}$ respectively.} They delineates
the \emph{GALEX}/NUV extinction map of about a third of the sky mainly at the
high Galactic latitude area with an angular resolution of $\sim 0.4\,\, \rm
deg$. The mean color excess ratio in the entire sky areas is derived to be
3.25, 2.95 and -0.37 for $E_{{\rm NUV,G_{BP}}} / E_{{\rm G_{BP},G_{RP}}}$,
$E_{{\rm FUV,G_{BP}}} / E_{{\rm G_{BP},G_{RP}}}$ and $E_{{\rm FUV,NUV}} /
E_{{\rm G_{BP},G_{RP}}}$ respectively, which is in general agreement with the
previous works, and their changes with the Galactic latitude and the
interstellar extinction are discussed.
