A large gear involute artifact assembled with mandrel used as physical datum of precision traceability and measurement transmission for large gear involute is proposed. The artifact comprises a large gear involute artifact stripe, a mandrel, a backing plate, a counterweight shaft, an adjustable counterweight ring, the adjustable screws of counterweight, the connecting screws for backing plate, the connecting screws for artifact and an eccentric multi-ball bearing. The structure and the rolled length of the large gear involute artifact assembled with mandrel fit the basic requirements of class-1 accuracy in the national standard of gear involute artifact GB/T 6467-2010 in China. It has advantages of long rolled length, adjustable center of mass, uniform datum, compact structure, and portability. It adopts lightweight design, which can be installed and transported by one person manually, and is suitable for the structural design of large gear involute artifact with base-circle diameter greater than 500 mm.