The girl began showing symptoms -- fever, cough, sore throat and headache -- Thursday and was brought to the Beijing Ditan Hospital, where she was held for treatment of a lung infection, the BBC reported.
Hospital officials said two people who were in close contact with the girl have not shown signs of bird flu.
The girl's case brought the total number of people infected with the H7N9 strain of bird flu in China to 44, China's official Xinhua news agency said. There have been no reports of the H7N9 strain abroad.
The National Health and Family Planning Commission said 11 of the H7N9 patients had died as of Friday.