East of Tainan City, Guanmiao is situated in the south side of Tainan County not far pass the Guanmiao Rest Station on Highway 2S. Geographically, Guanmiao borders Sinhua at north, Longci at east, Gueiren at west, and Tianliao/ A Lian (Kaohsiung County) at south. Gueidong Village of Guanmiao Township is the southernmost part of Tainan County at 120”21’E and 22”53’N.
Geologically, Guanmiao is at the borderline of Jianan Plain and Sinhua Barrows, sloping to the west like a dustpan. Slow barrows spread across the townships with the highest mountain – Jianshan marking 1368 meters above sea level. Bamboo woods are the main feature of this township as well as pineapple plantations. At the upper stream of Sanlao Creek, Susian Creek, a branch of Yanshuei Creek, flows by at north; south of Guanmiao lies the water system of Erren Creek, and its branch, Fanshe Creek, divides Tainan County from Kaohsiung County, which was a habitat of the earliest dwellers of Guanmiao – the Sirayas, as well as the earliest development point of the township.