Fenyi County () is a county of and one of two divisions of the prefecture-level city of Xinyu, in the northwest of Jiangxi province, the People's Republic of China.
The population in 2017 was .
In the present, Fenyi County has 6 towns and 4 townships.
Fenyi Country has a humid subtropical climate with abundant rainfall and sunshine, and a long frost-free period. It has an average yearly temperature of 17.2 degrees, average annual rainfall of , and a frost-free period of 270 days.