  Magnetography using magnetic sensitive lines is regarded traditionally as the
main instrument for measuring the magnetic field of the whole Sun. Full
polarized Stockes parameters ($I$, $Q$, $U$, $V$) observed can be used to
deduce the magnetic field under specific theoretical model or inversion
algorithms. Due to various reasons, there are often cross-talk effects among
Stokes signals observed directly by magnetographs. Especially, the circular
polarized signal $V$ usually affects the linear polarized ones $Q$ and $U$
seriously, which is one of the main errors of the value of the transverse
magnetic field (parallel to the solar surface) that is related to $Q$ and $U$.
The full-disk magnetograph onboard the Advanced Space based Solar Observatory
(ASO-S/FMG) is designed to observe Stockes parameters to deduce the vector
magnetic field. In this paper, the methods correcting the effects of cross-talk
$V$ to $Q$ and $U$ are based on the assumption of perfectly symmetric Q and U
and anti-symmetric Stokes V profiles and a new method to reduce the crosstalk
effect under observation mode of FMG is developed. Through the test, it is
found that the two methods have better effect in cross-talk removal in the
sunspot region, and have better consistency. Addtionally, the developed
methodcan be applied to remove the cross-talk effect using only one group of
$Q$, $U$ and $V$ images observed at one wavelength position.
