  In 2022 China Space Station (CSS) will be equipped with atomic clocks and
optical clocks with stabilities of $2 \times 10^{-16}$ and $8 \times 10^{-18}$,
respectively, which provides an excellent opportunity to test gravitational
redshift (GR) with higher accuracy than previous results. Based on high-precise
frequency links between CSS and a ground station, we formulated a model and
provided simulation experiments to test GR. Simulation results suggest that
this method could test the GR at the accuracy level of $(0.27 \pm 2.15)
\times10^{-7}$, more than two orders in magnitude higher than the result of the
experiment of a hydrogen clock on board a flying rocket more than 40 years ago.
