An-nan District is located at the southwest tip of Tainan City. It borders the Taiwan Strait in the west and Anping District, Midwest District and East District in the south with the Yanshui River. In the north, it is adjacent to Qigu District and Xigang District. And it is next to Yongkang District and Anding District in the east.
The Precinct covers an area of 107.2 km2, which is divided up into 51 villages and 856 neighborhoods. Currently there are a total of 63,587 households with a population of 193,009. In the east and north, the Precinct is next to Yongkang and Shanhua Precincts by the Yanshui River. In the south, it is next to Fourth and Fifth Precincts where the Yanshui River and Jianan Irrigation Canal are merged and exit to the ocean. In the north, there is Zengwen River that passes through the Precinct as it makes its exit to the ocean and borders with Jiali Precinct. The coastline is 14km long with its southwest facing the Taiwan Strait.
There are mostly farmlands, lands for industrial use and fisheries within the Precinct. The residents mostly rely on farming and trading. Its people live a simple life and are close with one another in a supportive and genuine way. Inside the Industrial District, there are three regions: Zong Tou Liao, He Shun and Tainan Technology.