It is the largest firm order to date for Boeing's new fuel-efficient jet and gives Chicago-based Boeing a boost in its competition with European rival Airbus SAS (search) for business in China.
The first of the jetliners will be delivered in 2008, Xiamen Airlines Co. (search) said in a statement.
Xiamen Airlines said it plans to introduce a 7E7 aircraft to its service each year during 2008 and 2010.
On Thursday, Boeing spokeswoman Amanda Landers said Boeing had "reached a substantial agreement" on the sale but declined to provide more detail.
The 7E7 Dreamliner, which is expected to go into service in 2008, competes with the A350 being developed by Europe's Airbus SAS. The Toulouse, France-based company expects to put its plane into service by 2010.
At the end of last year, Boeing had firm orders for 56 of the planes and tentative agreements for an additional 70 planes.
Boeing's twin-aisle Dreamliner comes in three models, able to seat between 223 and 296 passengers with a range of up to 9,800 miles. Boeing says it will be 20 percent more fuel-efficient than comparable airplanes on the market today.
Boeing has said the 7E7 will be priced at about $120 million, though airlines usually negotiate discounts for large orders. The plane will be assembled in Everett, about 30 miles north of Seattle.
The largest order by a single airline for the 7E7 was placed last spring, when All Nippon Airways (search) of Japan ordered 50.