The Shenzhou-23 vessel is scheduled to launch at 11:08pm (1:08am Monday AEST) using the Long March-2F Y23 carrier rocket from Jiuquan Satellite Launch Center in northwest China, with three Chinese astronauts on board.
Payload specialist Li Jiaying, a former Hong Kong police inspector, will be the first astronaut from the city to take part in a Chinese space mission. The other crew members are commander Zhu Yangzhu and pilot Zhang Yuanzhi, both from the People's Liberation Army's astronaut division.
One of the three is to stay on the Tiangong space station for a year, one of the longest space missions ever but short of the 14-and-a-half month record set by a Russian cosmonaut in 1995.
That astronaut will be decided later, depending on the progress of the mission, the China Manned Space Agency said on Saturday.
China has sent astronauts to its space station almost a dozen times, but this launch comes amid an accelerating race to the moon with the US, which has warned about what it alleges are Beijing's plans to colonise and mine lunar territory and resources.
Beijing has strongly rejected these claims.
NASA is seeking to achieve a crewed moon landing in 2028, two years ahead of China.
The US aims to establish a long-term lunar presence as a stepping stone to eventual human exploration of Mars.
On Friday Elon Musk's SpaceX made a largely successful, uncrewed test flight of its next-generation Starship rocket, which is designed to enable more frequent Starlink satellite launches and to send future NASA missions to the moon.
China, with less than four years until its 2030 deadline, faces a tall order of developing entirely new hardware and software specific to its lunar mission, proving it is mission-ready.
China's Shenzhou missions have been sending trios of astronauts to the station for six-month stays since 2021.
A successful crewed landing before 2030 would boost China's plans to establish a permanent base on the moon by 2035 with Russia.
Beijing is conducting the world's first human "artificial embryo" experiment in space, having sent samples of human stem cells to the Shenzhou-22 crew on the Tiangong this month, state media reported.
The experiment is intended to study the long-term residence, survival and reproduction of human beings in space.
