In recent history, four major Chinese Romanization transcription systems have offi cially been adopted in Taiwan, namely the General Chinese Phonetic Alphabet (GCPA), the Wade-Giles Scheme (WGS), the Mandarin Phonetic Symbols II (MPS II) and the Scheme of Chinese Phonetic Alphabet (SCPA). The advantages and disadvantages of these four systems have been a focus of discussion by researchers. Based on a quantitative comparison of six indices on the phoneme-grapheme relationship,this study attempts to analyse the features of each of four systems. The fi ndings show that WGS achieves the lowest in all of six indices and MPS II performs higher than those of WGS in four indices; although almost all indices of GCPA are superior to those of WRS and MPS II, it is SCPA that gains an advantage over those of GCPA in four indices. Based on the relationship between grapheme and phoneme and the degree of system optimization, the current study shows that, out of the four systems examined in this paper, SCPA is the best Chinese Romanization transcription system in both graphic representation of phoneme and economic efficacy in linguistic resource utilization. It is my hope that the use of quantitative indicators provides a new methodology and perspective for the formulation and evaluation of language policies.