Will you have an International->International or other transfer in Beijing Capital Airport(https://www.travelchinaguide.com/cityguides/beijing/capital-airport.htm) ? If you have connected air ticket, the luggage will be transfer to your next flight automatically. In this case, you don't have to bring your luggage. But, you have to check-in again once leaving the airport. Actually, it is not suggested that you leave the airport since the transportation to and from downtown Beijing will take one hour for one-way trip at least.