The Shenzhou-12 manned spaceship is expected to launch at 9:22 am on Thursday Beijing time from the Jiuquan Satellite Launch Center in Northwest China, according to the mission command center.
The spaceship will take astronauts into space for the construction of China's space station.
The crew consists of astronauts Nie Haisheng, Liu Boming and Tang Hongbo.
Zhai Zhigang, Wang Yaping and Ye Guangfu will be the backup crew.
Nie has participated in the Shenzhou-6 and Shenzhou-10 manned missions and Liu has joined in the Shenzhou-7 manned mission. Tang will make his debut in this mission.
After entering orbit, the spaceship will conduct a fast automated rendezvous and docking with the in-orbit space station core module Tianhe, forming a complex with the core module and the cargo craft Tianzhou-2.
The Shenzhou-12 crew will have a three-month stay in the core module, according to the mission plan.
The launch will be carried out with a Long March-2F carrier rocket, which will be filled with propellant on Wednesday morning.