Chinese media reported on Monday that one-third of the structure can still be characterised as a wall, one-third is merely made up of piles of rock and bricks and one-third has entirely disappeared.
The Beijing Daily said much of the destruction had been caused by humans, as generations of farmers had torn out pieces of wall to get raw material when they built new homes, stables or repaired fences.
The state of the Great Wall is such that the World Monuments Fund has put it on a watchlist of the planet's 100 most endangered structures, according to the newspaper.
This is the second recent blow to the Great Wall after China's first astronaut Yang Liwei said in October that he could not see it from space, contrary to the belief of many Chinese.
Sucessive Chinese emperors, beginning with the Qin Dynasty in the late 3rd century BC, built or improved on the Great Wall in order to keep out northern tribes constantly posing a threat to the Chinese heartland.