4 13000。 According to the national postal code database, the postal code of Yiyang City, Hunan Province is 4 13000. Postal codes are arranged in four levels and six digits, with the first two digits 4 1 representing Hunan province, the third digit 3 representing Yiyang city, the fourth digit 0 representing county or district postal area, and the last two digits 00 representing specific delivery address.