Tianlin's population was 245,800(2010). 63.06% of the people belong to the Zhuang ethnic group. The rest include Yao, Han, Miao,and other ethnic groups.
Ethnic Yao are distributed mostly in the townships of Lizhou 利周, Lucheng 潞城, Bagui 八桂, Nongwa 弄瓦, Fuda 福达, and Badu 八渡, while ethnic Yi are found in Changjing Village 常井村 of Ding'an Township 定安镇.
The Miao of Tianlin County call themselves "Mengxia 孟夏", while the Zhuang call themselves Puyue 甫越 (bu33 jui33), the Han call themselves Kebianren 客边人 ('guest people'), and the Yi call themselves Buna 布那.