For Ching China, forts were important means to control and manage Taiwan. Surrounded by thousands of miles of seashore, Taiwan was difficult to defend; thus, Ching China put her main coast defence in Tainan, Ching's base in Taiwan. Since the 17th century, due to many changes of geographical features and topography in Tainan and its neighbor, An-ping, forts were often re-established. This paper will examine the history of the establishment of these forts, especially why and how Ching China re-established these forts, and the relationship between the rise and fall of Tainan as Ching China's base in Taiwan and the re-establishment of forts in Tainan.