What is the distance from United (International) gates to China Eastern Air (Domestic) at PEK?

You need transfer from T3 to T2, and it is about 4.5 miles between these two terminal buildings. There are free shuttle buses that you can take, and the bus ride is about 10 mins.

I’m afraid your time is not enough. As I know the transfer international to domestic, T3 to T2, needs at least 160 mins, so 2 hours are not sufficient.

In the official website, there is a map available, but you do not need to worry about it, for there are signs in English indicating the direction, you will find your way.