The aim of this paper is to integrate the phonetic experiments with the phonological theories. I will argue that there is no true gemination in Taiwanese and then explore Taiwanese syllable structure. It is commonly assumed that Taiwanese syllable-final /ptk/ sounds undergo gemination before the diminutive/nominalized suffix /a/, e.g., "/ap-a/ -> [abba]" ([3]). However, the results of our duration experiments reveal that the previous impressionistic view is untenable. Gemination does not in fact occur. Instead, /p,k/ undergo free variation, i.e., vocing or spirantization, while A/ is flapped. As for syllable break, resyllabification and foot-internal structure are separately proposed. To reinforce the above observations, the phenomena of quality (iptkJ), quantity (CIV length) and tone sandhi are provided.