The vast majority (>90%) of Chinese are Han Chinese. The remainder are distributed among 55 other ethnic groups
. This diversity was awkwardly displayed during the opening ceremonies of the last Olympic games, when a parade of 56 children representing those groups was later revealed to have been comprised of 56 Han Chinese children wearing the ethnic clothing of the other groups.
Now there is a photoessay which appears to correct that gaffe. All of the ethnic groups are portrayed in professionally composed group portraits, with the subjects wearing traditional dress and often carrying traditional instruments or tools. Pictured above as an example are the ethnic Kazak; the others are at the link. It's an impressive photo gallery.Link