If you want a cheap flight from Boston to Beijing, you've got one airlines to choose from.
Beijing Capital Int. Airport is just one of the airports in Beijing. If you're not set on a specific airport, try changing your search from Beijing Capital Int. Airport to Beijing to see a broader range of flights – they might be cheaper. It usually takes about 21 hrs 50 mins to fly 10825 km to Beijing Capital Int. Airport.
five flights go to or via Beijing every week. The most popular airline is Cathay Pacific but do spend some time checking all your options – they aren’t necessarily the cheapest airline to book with.
If you're planning on going to Beijing during this time, you could take a look at other airport options. Or you could try to get a last-minute bargain.