The 5-foot landmark, which honors the memory of Danish fairy tale writer Hans Christian Andersen, was lifted by a crane and lowered onto the back of a truck at a ceremony in the Danish capital.
The exact travel itinerary is being kept secret for security reasons, but the statue is scheduled to be placed in the Danish pavilion about a week before the World Expo opens May 1.
The temporary move is controversial in Denmark, where some considered it disrespectful to ship a cultural treasure halfway across the globe as a PR tool. Critics suggested the government should have sent a copy to China - an idea dismissed by Christopher Bo Bramsen, Danish commissioner-general for Expo 2010.
"Why send a copy when you can send the real thing?" he told The Associated Press.
Bramsen joined Copenhagen Mayor Frank Jensen and officials from the Danish government and the Chinese Embassy at the ceremony, which featured music and dance performances by Danish and Chinese artists.
Hundreds of people who had gathered for the event watched as a large crane hoisted the statue about 10 feet and slowly moved it over to the truck. The mermaid and the rock she rests on had been cut loose from the boulders beneath them a day earlier.
The fishtailed bronze is Denmark's most popular tourist attraction. Created by Danish sculptor Edvard Eriksen, the mermaid had not moved from the Copenhagen harbor since she was unveiled there in 1913.
"I think they should keep her there. She doesn't represent Danish life in the 21st century they should have sent something else," said Sarah Ahmed, a 16-year-old student in the crowd.
Anne-Marie Henning, 92, said she would miss the mermaid.
"I have been coming here for years as I live in the neighborhood. It will feel strange without her," Henning said.
A video installation by Chinese artist Ai Weiwei will replace the Little Mermaid until the statue returns in November. The multimedia artwork will include a live broadcast of the statue in Shanghai.
In Andersen's tale, the mermaid is a sea king's daughter who falls in love with a prince and must wait 300 years to become human. It was turned into a Disney film in 1989.
Over the years the statue has repeatedly been targeted by vandals: she's been decapitated, covered in paint and had her right arm cut off.