Air China is to order two Boeing 747-8s and 20 737s as well as nine 777s, eight of which will be freighters for its cargo division.
The carrier has disclosed the arrangement in a statement to the Hong Kong stock exchange.
It says the flag-carrier will take two passenger 747-8s and a 777-300ER along with 20 737-800s, while Air China Cargo has agreed to purchase eight 777Fs.
Boeing has also agreed to purchase seven 747-400BCF freighters from the cargo operation.
Under the agreement Air China has the option of converting four of the 737-800s into a single 777-300ER.
The passenger aircraft will be delivered in stages over 2014-15, while the freighters will arrive during 2013-15.
Air China values the passenger jets at $2.6 billion and the freighters at $2.2 billion.
All the 777s will have General Electric GE90 engines as standard, while the GE GEnx engine will power the 747-8s. The 737s are exclusively powered by CFM International CFM56s.