Air China (CA) is a Star Alliance member based in Beijing (PEK). It is mainland China’s flag carrier, with long-haul routes to North America and Europe plus a huge domestic network. Award availability to partners is generally decent, including in premium cabins, which makes it a workable option for getting to China on Star Alliance miles.

Because Air China is in Star Alliance, you can book its award space with partner miles, including:
The easiest place to search is the United Airlines website. United displays Star Alliance partner availability, including Air China, and you can search without holding any miles.
Log in to your United Airlines account on united.com. If you don’t have an account yet, signing up is free.
Select the Book Travel box and fill in your trip details:
Then click Search.
Pick the flight option that fits your schedule. Watch the connection times carefully, as some options have very long layovers.
If you would like to search a different day, use the calendar to scan nearby dates. Availability drops sharply around Chinese New Year and Golden Week, so avoid those windows if you can.
Make sure you select the Saver Award, as standard awards cost far more miles and usually can’t be booked with partner programs anyway.
Choose your preferred flight and open its details. Write down the following information: flight number, dates, and cabin class.
Now book with the program your miles live in. If it’s United miles, book right there on united.com. For other programs (Aeroplan, LifeMiles, Miles&Smiles), check their website first, since most can book Star Alliance partners online now. If the flight doesn’t show, call the program and read the agent the exact flights you found. They should be able to see and book the same space for you.