Liu, along with Zhai Zhigang and Jing Haipeng, was chosen to be the main crew of Shenzhou 7, with Zhai as commander, on 17 September 2008. On 25 September, at 21:10 CST, they launched into space as China's third human spaceflight mission, and the first Chinese mission ever to have a three-man crew.[2] Liu and Zhai participated in China's first-ever space walk.
Liu wore a Russian Orlan-M spacesuit, while Zhai wore the Chinese-made Feitian space suit. Liu remained in the open portal of the orbital module, assisting Zhai on his spacewalk; later in the space walk, Liu also performed a stand-up extra-vehicular activity, partially leaving the orbital module in order to hand Zhai a Chinese flag.[3] After the spacewalk, Liu said in an interview that his inspiration and idols have always been Neil Armstrong and Yuri Gagarin.[4]
In 2018, he became a PhD candidate at Beijing Institute of Technology.[5]
On 17 June 2021, Liu flew on Shenzhou 12 as his second spaceflight, becoming one of the three initial crew members to enter the Tiangong space station.[6][7] On 4 July 2021, Liu and Tang Hongbo, another crew member of Shenzhou 12, completed the first extravehicular activity of the Tiangong space station.[8] On 20 August 2021, Liu and mission commander Nie Haisheng carried out the second extravehicular activity of the space station,[9] making him the first Chinese national to perform extravehicular activities multiple times.