It was the first time the Chinese astronauts had entered the lab module in orbit.
The Wentian module, launched on Sunday afternoon, docked with the front port of the Tianhe core module at 3:13 a.m. Monday.
The astronauts will conduct in-orbit work such as the attitude control of the combination of the space station, small mechanical arm crawling and the test of the complex of big and small arms.
They will also use the airlock cabin and the small mechanical arm of Wentian to carry out extravehicular activities.