  The role of HI content in galaxy interactions is still under debate. To study
the HI content of galaxy pairs at different merging stages, we compile a sample
of 66 major-merger galaxy pairs and 433 control galaxies from the SDSS-IV MaNGA
IFU survey. In this study, we adopt kinematic asymmetry as a new effective
indicator to describe the merging stage of galaxy pairs. With archival data
from the HI-MaNGA survey and new observations from the Five-hundred-meter
Aperture Spherical Radio Telescope (FAST), we investigate the differences in HI
gas fraction ($f_{\text{HI}}$), star formation rate (SFR), and HI star
formation efficiency ($\rm SFE_{\text{HI}}$) between the pair and control
samples. Our results suggest that the HI gas fraction of major-merger pairs on
average is marginally decreased by $\sim 15\%$ relative to isolated galaxies,
implying mild HI depletion during galaxy interactions. Compared to isolated
galaxies, pre-passage paired galaxies have similar $f_{\text{HI}}$, SFR and
$\rm SFE_{\text{HI}}$, while pairs during pericentric passage have weakly
decreased $f_{\text{HI}}$ ($-0.10\pm0.05$ dex), significantly enhanced SFR
($0.42\pm0.11$ dex) and $\rm SFE_{\text{HI}}$ ($0.48\pm0.12$ dex). When
approaching the apocenter, paired galaxies show marginally decreased
$f_{\text{HI}}$ ($-0.05\pm0.04$ dex), comparable SFR ($0.04\pm0.06$ dex) and
$\rm SFE_{\text{HI}}$ ($0.08\pm0.08$ dex). We propose the marginally detected
HI depletion may originate from the gas consumption in fuelling the enhanced
$\rm H_2$ reservoir of galaxy pairs. In addition, new FAST observations also
reveal an HI absorber ($N_{\text{HI}}\sim 4.7 \times 10^{21} \text{ cm}^{-2}$),
which may suggest gas infalling and the triggering of AGN activity.
