A giant new airport has opened outside the Chinese capital, just days before the country celebrates its 70th anniversary.

Bejing Daxing airport, reportedly the largest single-building terminal in the world, is expected to receive a significant amount of the 170m passengers expected to arrive in Beijing annually by 2025. It is located 46km south of Tiananmen Square and cost NZ$17.4 billion.

The airport spans 700,000 square metres according to state media outlet China Daily, the equivalent of 98 soccer fields. President Xi Jinping opened the airport on Wednesday.

Seven domestic airlines were expected to begin operations out of the new 'starfish' airport on Wednesday, with the first flight - a China Southern Airlines A380 - taking off at 16:23 local time.

Bejiing Capital airport sees more than 100 million passengers a year, and opened in 1958. With the opening of Daxing, the city joins a host of other global cities, including New York and London, with two or more long-haul international airports.