According to Google's flight information software, flight 783 was delayed nine hours.
Air China's website said the flight left at 2pm Auckland time.
Air China's Auckland office has not yet returned a message seeking comment on the flight.
Auckland Airport still expected the flight to arrive on time, but said this information depended on details the airline supplied to the airport.
Flights between the two cities typically take about 13 hours.
In September, Air New Zealand and Air China announced joint sales for a new daily direct service between Auckland and Beijing.
Smog has caused cancellations and delays at Beijing's airports several times in the past few years.
Authorities in Beijing issued their second-ever alert for dangerous air quality on Friday, the New York Times reported.
"The widespread pollution has several causes: growing industrialisation, China's heavy reliance on coal, and the ability of air pollutants to travel far from their sources, even in a light breeze," the Times added.