  We present the results from the NICER observation data of MAXI J1803-298
across the entire 2021 outburst. In the intermediate and soft state, we detect
significant absorption lines at $\sim 7.0$ keV and $\sim 6.7$ keV, arising from
the X-ray disk wind outflowing with a velocity of hundreds of km per second
along our line of sight. The fitting results from photoionized model suggest
that the wind is driven by thermal pressure and the mass-loss rate is low. We
find a clear transition for iron from predominantly H-like to predominantly
He-like during the intermediate-to-soft state transition. Our results indicate
this transition for iron is caused by the evolution of the illuminating
spectrum and the slow change of the geometric properties of the disk wind
together. The coexistence of disk wind and QPOs features in intermediate state
is also reported. Our study makes MAXI J1803-298 the first source in which a
transition from optical wind to X-ray wind is detected, offering new insights
into the evolution of disk winds across an entire outburst and long-term
coupling of accretion disks and mass outflows around accreting black holes.
