5 17500。 According to the inquiry of official website, the people's government of Dongyuan County, the postcode of Dongyuan County, Heyuan City is 5 17500. Dongyuan County, which belongs to Heyuan City, Guangdong Province, is located in the middle and upper reaches of Dongjiang River in the northeast of Guangdong Province, bordering Longchuan County and Wuhua County in the east, Yuancheng District and Zijin County in the south, Longmen County and Xinfeng County in the west, and peace county and Lianping County in the north, with a total area of 4,070 square kilometers.