The 56 Official Nationalities in China (in descending order of population size):

Han Chinese
Zhuang
Manchu
Hui (Muslim)
Miao
Uygur
Yi
Tujia
Mongol
Tibetan
Bouyei
Dong
Yao
Korean
Bai
Hani
Dai
Li
Kazak
She
Lisu
Gelao
Lahu
Dongxiang
Shui
Wa
Naxi
Qiang
Tu
Xibe
Mulao
Kirgiz
Daur
Jingpo
Salar
Bulang
Maonan
Tajik
Monba
Pumi
Achang
Nu
Ewenki
Jing
Jino
De'ang
Uzbek
Russian
Bonan
Yugur
Lhoba
Oroqen
Derung
Tatar
Hezhen
Gaoshan (only about 3,730 live on mainland China - many more in Taiwan)

(I'll add the chinese character in later on)