Air China Flight 1350 from Changsha to Beijing was diverted to Zhengzhou after a crew member was held hostage by the male passenger.
The Civil Aviation Administration of China (CAAC) said the man used a pen to threaten the crew member.
The flight took off from Changsha, the capital of southern Hunan province, at 8:40am (local time) and was scheduled to arrive at Beijing Capital International Airport at about 11:00am.
But it made the unscheduled landing at Zhengzhou Xinzheng International Airport, in central Henan province, at 9:58am, according to Henan Airport Group.
"The incident was successfully dealt with at 1:17 p.m. and passengers and crew members are safe," the CAAC said.
A 41-year-old man from Anhua with a "history of mental illness" has been taken into custody over the incident, Shanghai-based online news outlet 'The Paper' quoted police as saying.
All passengers on board the flight were safely evacuated through the rear exit and the man was subdued after 1pm, Hong Kong based South China Morning Post reported.
"Presently the airport is operating as normal," the Henan Province Airport Group said.