The world-famous stargazer is 65 and has lived at his home in southern China for more than 30 years, his daughter said on Sunday.
Mr Liu, the oldest person ever to fly solo across the cosmos, spent the first few months of his life at the Beijing Observatory in northern China before heading to the observatory in the south, his wife Li Li told reporters in a rare interview.
“He was the oldest living person in the world, and I think the world knows it,” Ms Li said, referring to the Beijing observatory.
“And he was the world’s longest-living person in history.”
“His condition is not very good.
We don’t know what his condition is, but we know that he is a good man,” she added.”
We know he is very active, he has a lot of energy.
He is not suffering.”
Mr Liu is the oldest human being who has ever been in space, having spent nearly three decades in orbit before retiring in 2005.
He is survived by his wife, Li, who died in January, his brother, Li Qiang, and three grandchildren.
The last time he flew solo was in 2007, but Mr Liu is survived in China by a son, Zhang Yufeng, who is in his early 70s.
“I feel like he is in a very good place,” Mr Liu’s daughter said.
“If there is a doctor who could help me, I would want to go and see him, and he is already in good health,” she said.
Ms Li said Mr Liu was “always very busy” in the observatories garden and had spent most of his time at the observance with his family.
“But he has been at the site a lot,” she explained.
“So he knows a lot about the ground and the weather.”
“He’s very interested in the atmosphere and astronomy.”
China has had its share of stargazers, but few have had as long a tenure in space as Mr Liu.
Born in 1919 in southern Beijing, Mr Liu joined the Communist Party at a young age and joined the People’s Liberation Army in 1937.
After serving in a variety of roles in the People on the Moon, he became a full-time space traveller in the late 1960s, returning to China after serving two years as a research fellow at the American National University.
Mr Mao, the Communist leader, appointed him to the newly created Central Committee in 1968 and appointed him the head of the Communist People’s Republic of China.
“In his lifetime, Mr Jiang has been the longest-serving director of the observator,” Ms Lin said.
Mr Jiang was a prominent figure in China’s space programme, serving as the country’s ambassador to the United Nations and the chairman of the Chinese Academy of Sciences.
“As the chairman and president of the Central Committee, he also had a great responsibility for the development of the space program,” Ms Zhou said.
She said Mr Jiang was “one of the founding fathers of space science and technology” in China.
The International Astronomical Union (IAU) named him the first Chinese astronaut to fly in space in 1976.
In 2006, he was awarded the China Space Prize for his work.
The IAU has awarded Mr Liu its prestigious Distinguished Service Medal, which is given to a space pioneer for his contributions to science, technology and engineering.
“Mr Jiang’s contributions to the development and utilization of space technology were significant and significant to humankind and to space exploration in general,” the organisation said in a statement.
“His contribution to space science was of such immense magnitude and the importance of this work cannot be overestimated,” it said.