A German art student briefly fooled police by posing as one of China's terracotta warriors at the heritage site in the ancient capital, Xian.
Pablo Wendel, made up like an ancient warrior, jumped into a pit showcasing the 2,200-year-old pottery soldiers and stood motionless for several minutes.
The 26-year-old was eventually spotted by police and removed from the scene.
Unearthed in 1974, the statues are said to be one of the 20th Century's greatest archaeological finds.
The ancient clay soldiers were created to protect the nearby tomb of the legendary Emperor Qinshihuang who united China over 2,200 years ago.
Police confiscated Mr Wendel's costume and sent him home
Mr Wendel is reported to have entered the museum on Saturday where he changed into his outfit, jumped over a barrier and took up a position on a pedestal he had taken along.
"I got to the area where he was supposed to be, looked around and didn't see him - he looked too much like a terracotta warrior," Hong Kong newspapers quoted a security guard as saying.
As Mr Wendel's "performance art" did not harm any of the ancient relics, he was not arrested or charged but given "serious criticism", the reports said.
Mr Wendel had his costume confiscated and was sent back to the eastern Chinese city of Hangzhou, where he is studying.