The blaze began around 5.30pm (8.30pm AEDT) in one of the parking berths and one person was injured, police said.
“When a loading vehicle was loading cargo onto the plane it caught on fire,” a police spokeswoman said, adding that it was an empty American Airlines flight.
More photos on the incident at Hong Kong airport today. Luckily cargo not loaded. pic.twitter.com/dUegiDe2TG
— ChinaAviationReview (@ChinaAvReview) October 9, 2017
Photos on social media showed the fire blazing, with black smoke rising near the belly of the plane in between the right wing and tail wing.
Hong Kong Airport Authority said the fire, which occurred at ground level, had been extinguished and they were investigating its cause.
The plane was bound for Los Angeles, according to the airport website.