Three flights to Baotou from Shanghai and Beijing were reportedly forced to circle the airport until the UFO disappeared.
Two other flights were diverted away from Baotou and to the nearby cities of Ordos and Taiyuan. The airport was shut for around an hour "to guarantee safety" according to a spokesman.
Witnesses reported a bright light shining in the sky on September 11 around two-and-a-half miles away from Baotou airport, before suddenly vanishing.
The incident was the eighth reported UFO sighting in China since the end of June.
Xiaoshan International airport near the eastern city of Hangzhou was shut down on July 8 because of a UFO, although officials later confirmed the object sighted above the airport had been part of a military test at a nearby airbase.
In the far-western province of Xinjiang, another sighting on June 30 is thought to have been a missile test.
A number of sightings in Sichuan province may also be linked to the local custom of flying illuminated kites at night.
The incident was the eighth reported UFO sighting in China since the end of June.
Xiaoshan International airport near the eastern city of Hangzhou was shut down on July 8 because of a UFO, although officials later confirmed the object sighted above the airport had been part of a military test at a nearby airbase.
In the far-western province of Xinjiang, another sighting on June 30 is thought to have been a missile test.
A number of sightings in Sichuan province may also be linked to the local custom of flying illuminated kites at night.
