Do I still need to go thru Immigration, Customs & get baggage at Beijing Capital Airport?

Flying Air China for all my flights.

Departure Flights
1:00 AM Leaving IAH Houston, Texas on Saturday, April 22, 2017 > Air China
4:50 AM Arriving PEK, China on Sunday, April 23, 2017 > Air China
(3H 30M Layover)
8:20 AM Leaving PEK, China on Sunday, April 23, 20117 > Air China
12:30 PM Arriving OKA Okinawa, Japan on Sunday, April 23, 2017 > Air China
RETURN FLIGHTS
Same on Return only for May 24, 2017