If you want a cheap flight from Cardiff to Shanghai, you've got one airlines to choose from.
Shanghai Pu Dong Airport is just one of the airports in Shanghai. If you're not set on a specific airport, try changing your search from Shanghai Pu Dong Airport to Shanghai to see a broader range of flights – they might be cheaper. It usually takes about 17 hrs 55 mins to fly 9398 km to Shanghai Pu Dong Airport.
two flights go to or via Shanghai every week. The most popular airline is Qatar Airways 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 Shanghai during this time, you could take a look at other airport options. Or you could try to get a last-minute bargain.