The Township is located between east longitude 120° 11’ and north latitude 23° 35’. It borders Dongshih Township to the east, Sihhu Township to the south. The old Huwei Stream separates Tasi from Mailiao Township. The west of the Township is the Taiwan Strait and the distant Penghu County. The Township is 5.95km wide, 11.125 long and the total area is 66.472 km2. The total area of Taisi Reclamation is 690 hectares and Sinsing Reclamation is 375 hectares large.
In spring, the Township usually has southwest wind, and the temperature is usually high. In autumn and winter, with strong northeastern monsoon, the weather is usually cold. The rainy seasons are spring and summer. The annual precipitation falls during this period is usually around 1,000 mm. The average temperature of the Township is around 22℃.