Abstract: As the nationality with the largest population in the world, the Han nationality has undergone a gradual process like a snowball in its formation and growth. The clan structures were complex during its formation, then they merged each other for more than 2000 years, mainly including the merger of the three clans of Xia, Shang and Zhou and the expansion toward other ancient tribes. The clan recognition during this time also went through a turn from scattering to centralization.

Key words: the Han nationality, clan structure, clan recognition, snowball