Dongshih Township is located along the coast to the west of Chianan Plain, with a coastline of about 14km in length. Being an alluvial plain, its area is about 82 square kilometers. The whole township is made up of 23 villages, bordering Puzih City in the east with Lioujiao Township as the border. Facing Waisandin Barrier Island in the west, it neighbors Beigang River and Kouho Township of Yunlin County in the north. With three brooks flowing through the township into the sea, they are the Puzih River, Lioujiao Drain, and Beigang River.
As our township is located by the sea, it is submerged under the sea level, causing salinization of the land. Therefore, the inarable lands have been converted to fish farms. At present, there are about 2000 hectares of fish farms on land in the township. As to the west coast, it was an important production area of salt in early Taiwan. Now, salt baking is not cost effective so many of the salt farms have ceased to operate. However, many of the salt fields remains intact, forming a unique site in the township.
As to the external transportation, Chi Route-168 and Tai Route-17 are major connections to other parts of the road system. In addition, Tai Route-61 and Tai Route-82, east-west expressways, lead to the township. At Wangliao Village, there is an interchange, constituting a convenient transportation network to the township.