China Southern Airlines has disclosed that it is ordering 20 Airbus A350-900 twinjets.
The airline revealed the agreement in a statement to the Shanghai stock exchange.
It says the Rolls-Royce Trent XWB-powered aircraft are the subject of a purchase contract, valuing the deal at around $6 billion.
"The actual price will be significantly lower than the catalogue price," adds the airline.
China Southern operates a wide range of Airbus types from the A319 up to the A380, but has not previously ordered the A350.
It says the 20 aircraft will be delivered in stages with six arriving in 2019, another six in 2020, and four each arriving in 2021 and 2022.