While several major airlines fly to Beijing, Shanghai, Guangzhou and Hong Kong, budget seats can prove hard to come by. For good offers, book as early as you can.
Particularly busy periods are usually when Chinese students are flying home for summer, flying back to universities around the world after summer or around Chinese New Year (early February). Tickets at these times are often hard to get and/or more expensive.
If you live somewhere like Toronto or San Francisco with a large overseas Chinese community, check for cheap flights with someone in that community. Sometimes flights advertised only in the Chinese newspapers cost significantly less.
Tiger Airways, Bangkok Airways. Air Asia and Cebu Pacific offer low-priced flights from Southeast Asia (Bangkok, Chiang Mai, Singapore, Kuala Lumpur and Manila) to various destinations in southern China, including Xiamen, Jinghong, Guangzhou, Haikou and Macau.
Oasis Airways offers cheap no-frills flights between Hong Kong and London. The lowest fares are HK$1000 (US$125) one way, typical more like HK$2500, and HK$6600 (US$825) for business class. Flights to Vancouver started mid-2007. Other European cities plus Oakland and Chicago in the US are reportedly planned for later.
Many fliers prefer Asian airlines, which generally have more cabin staff and better service. Hong Kong based Cathay Pacific is an obvious possibility for flights to China. Others include Singapore Airlines, Japan Airlines, and Indonesia's Garuda. Taiwan-based China Airlines does not fly to mainland China, but their Amsterdam-Bangkok-Taipei-Hong Kong route is sometimes cheaper than more direct flights and stopovers are possible.
Korean Air often have good prices on flights from various places in Asia, such as Bangkok via Seoul to North America. One person on a mailing list reported that taking a train to Southern China, cheap Macau-Bangkok flight, then Korean Air Bangkok-Seoul-LA was US$200 cheaper than flying direct Shanghai-LA. Korean Air also fly to a dozen or so Chinese cities, including Shanghai, but we do not know if the big discounts are available there.
China's own airlines are growing rapidly (500 planes in 2000, 863 as of May 2006; they say 1580 by 2010 and 3200 by 2024) and working hard at becoming highly competitive in both service and pricing. They include China Southern, China Eastern, and Air China.
North American airlines: Northwest serves Hong Kong, Beijing, Shanghai and Guangzhou through its hub at Narita. United has the most nonstops to North America, serving Hong Kong, Beijing, and Shanghai from Chicago, San Francisco and Washington. Continental Airlines flies to Hong Kong and Beijing from Newark, and American flies to Shanghai from Chicago. Delta Airlines will offer non-stop service from Atlanta to Shanghai starting in late-March 2008. Air Canada serves Beijing, Shanghai and Hong Kong from Toronto and Vancouver.
Flying from Australia, Qantas offer direct flights from Sydney, Melbourne, Brisbane and Perth to Hong Kong. [Qantas] also flies to Beijing and Shanghai from Sydney and only offers a code-share service to Shanghai from Melbourne.
Flying from New Zealand, Air New Zealand is the only direct option to Mainland China. They offer direct flights to Shanghai in the Mainland and Hong Kong.
European airlines: Air France flies from Paris to Guangzhou, Hong Kong, Beijing and Shanghai. British Airways goes to Hong Kong, Shanghai and Beijing. KLM fly direct Amsterdam-Chengdu, as well as to other Chinese cities. Finnair have a direct Helsinki-Guangzhou flight.
If you are coming into Hong Kong or Macau and then flying on to somewhere in mainland China, consider crossing the border to Shenzhen or Zhuhai and picking up a flight there. These are usually significantly cheaper.