The vast harbor on the Yangtze River estuary, including a wharf nearly 1 kilometer long and large buildings for manufacturing ship components, is nearly complete. Much of the harbor area appeared to be abandoned farmland just a year ago, according to earlier images CSIS analysed.
It dwarfs an existing harbor nearby, where destroyers and other warships are docked.
"We can see slow but steady progress on the hull, but I think the really surprising thing these images show is the extensive infrastructure buildup that has gone on simultaneously," said CSIS analyst Matthew Funaiole.
"It is hard to imagine all this is being done for just one ship," he added. "This looks more like a specialised space for carriers and or other larger vessels."
China's navy has recently launched four large Type 055 cruisers and its first large helicopter carrier, known as the Type 075.
China's military has not formally announced the plans for the third carrier, designated Type 002, but official state media have said it is being built.
The latest carrier would be somewhat smaller the 100,000-tonne "supercarriers" operated by the US but larger than France's 42,500-tonne Charles de Gaulle.
It is expected to be China's first carrier with a flat deck and catapult launch system, allowing the use of a wider range of aircraft and more heavily armed fighter jets.
China's first two carriers, which it has dubbed Type 001-class, are relatively small, accommodating only up to 25 aircraft that are launched from ramps built onto their decks. US carriers routinely deploy with nearly four times the number of aircraft.
Foreign military attaches and security analysts say the Type 001 ships are expected to essentially serve as training platforms for what they believe will be fleet of up to six operational carriers by 2030.