According to the postcode database, the postcode of Shangsi County, Fangchenggang City is 535500. Among them, 53 represents Guangxi Zhuang Autonomous Region, the third 5 represents Fangchenggang City, the fourth 5 represents Shangsi County, and the last 00 represents the deliverable area.

Shangsi County, a county under the jurisdiction of Fangchenggang City, Guangxi Zhuang Autonomous Region, is located in the southwest of Guangxi Zhuang Autonomous Region and the northwest of Fangchenggang City.