There are six airlines offering flights to Beijing. The most direct route isn’t necessarily the cheapest – being flexible is key to finding the lowest airfare rates. For example, try searching by month to see the best time of the week to fly. The cheapest date is currently 15 / Apr / 2019.
You can use the filters on your search to see more flights and find cheaper rates – Beijing has more than one airport. So if you don't need to fly into Beijing Capital Int. Airport, it's worth checking your other options. The 7991 km flight usually takes about 17 hrs 40 mins.
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.