  The China Space Station Telescope (CSST) will enter a low Earth orbit around
2024 and operate for 10 years, with seven of those years devoted to surveying
the area of the median-to-high Galactic latitude and median-to-high Ecliptic
latitude of the sky. To maximize the scientific output of CSST, it is important
to optimize the survey schedule. We aim to evaluate the astrometric capability
of CSST for a given survey schedule and to provide independent suggestions for
the optimization of the survey strategy. For this purpose, we first construct
the astrometric model and then conduct simulated observations based on the
given survey schedule. The astrometric solution is obtained by analyzing the
simulated observation data. And then we evaluate the astrometric capability of
CSST by analyzing the properties of the astrometric solution. We find that the
accuracy of parallax and proper motion of CSST is better than 1 mas( yr1) for
the sources of 18-22 mag in g band, and about 1-10 mas( yr1) for the sources of
22-26 mag in g band, respectively. The results from real survey could be worse
since the assumptions are optimistic and simple. We find that optimizing the
survey schedule can improve the astrometric accuracy of CSST. In the future, we
will improve the astrometric capability of CSST by continuously iterating and
optimizing the survey schedule.
