  Cross-correlating the data of neutral hydrogen (HI) 21cm intensity mapping
with galaxy surveys is an effective method to extract astrophysical and
cosmological information. In this work, we investigate the cross-correlation of
MeerKAT single-dish mode HI intensity mapping and China Space Station Telescope
(CSST) spectroscopic galaxy surveys. We simulate a survey area of $\sim 300$
$\mathrm{deg}^2$ of MeerKAT and CSST surveys at $z=0.5$ using Multi-Dark N-body
simulation. The PCA algorithm is applied to remove the foregrounds of HI
intensity mapping, and signal compensation is considered to solve the signal
loss problem in the HI-galaxy cross power spectrum caused by the foreground
removal process. We find that from CSST galaxy auto and MeerKAT-CSST cross
power spectra, the constraint accuracy of the parameter product $\Omega_{\rm
HI}b_{\rm HI}r_{{\rm HI},g}$ can reach to $\sim1\%$, which is about one order
of magnitude higher than the current results. After performing the full MeerKAT
HI intensity mapping survey with 5000 deg$^2$ survey area, the accuracy can be
enhanced to $<0.3\%$. This implies that the MeerKAT-CSST cross-correlation can
be a powerful tool to probe the cosmic HI property and the evolution of
galaxies and the Universe.
