Ren Xin, 11, was operated on by a team of specialists in Beijing - and Sky News reported that, judging by the expressions on doctors' faces, the operation was a success.
The extra arm came from an undeveloped parasitic twin whose spine was fused with Ren Xin's. A major blood vessel from the twin was connected to her organs, further complicating the potentially-fatal surgery.
Angel: Doctors prepare Ren Xin, 11, for surgery to remove her parasitic twin
Life-saving: The life or death operation was complicated as the twin's spine was fused with Ren Xin's
The operating team was led by one of China's most eminent surgeons, who said the "extremely complex and potentially dangerous" operation was very rare - with only four cases like it in all of China.
Ren Xin's parents - poor farmers from Shanxi province - brought their daughter to Beijing because the provincial hospitals were unable to help her.
Sitting up in bed before the operation she said: "I want to become a good doctor and a good daughter for my parents".
Future: The 'angel with wings' wants to become a doctor and be good daughter to her parents