Flying on Air China from New York via Beijing to Changsha, do I need to take luggage out in PEK?

Hi, I am flying with Air China all the way, take CA820 from New York to PEK, and then take CA1363 from PEK to Changsha. Do I need to take my luggage out in PEK to go through custom, or Air China will transfer my luggage from CA820 to CA1363 and I only need to take my luggage out in Changsha to go through custom? Please tell me. Thank you for your help.