本研究提出國內財務會計學界所慣用繁體中文可讀性指標CRIE數值和公司中文CSR報告書內容具體性呈反比之觀點，手動蒐集臺灣上市櫃公司在2015年至2021年間發布的CSR報告書內容，作為研究樣本，探討永續(ESG)績效與報告書CRIE數值之間的關聯，該指標數值倚重報告書中難詞的數量衡量其可讀性；本研究並使用台灣經濟新報資料庫中的TESG永續發展指標，於其三項支柱各面向實際績效，但排除資訊揭露程度部分之得分後取分數總和辨識ESG表現較佳或較差公司，以研究公司是否會因為ESG績效的領先或落後而在報告書中有難詞數差異。實證結果顯示，ESG績效表現優秀或大幅進步的公司，傾向於在其報告書中使用更多的難詞。而ESG績效表現較差的公司則傾向於減少難詞數量。對於ESG績效表現優異或大幅進步的公司，機構投資人的持股比率以及資本支出比率更進一步影響報告書中難詞的使用數。此結果顯示ESG績效表現優秀公司之溝通策略：使用更多的難詞能夠提供更具體且客觀的資訊。因此本論文提出以下建議：(1)研究者宜審慎使用可讀性指標，尤其是會計學界習用之CRIE指標，(2)報告書中的難詞數可幫助利益關係人區分企業之ESG實際績效究係為領先或落後。

This study proposes the view that the CRIE value, a Traditional Chinese readability index commonly used by Taiwan’s financial accounting circles, is inversely proportional to the specificity of the company’s Chinese CSR report content. This study hand-collects and examines the CSR reports issued by listed companies in Taiwan from 2015 to 2021 to explore the relationship between ESG performance and the CRIE value of the report. The CRIE setting relies on the number of complex words in the report to measure its readability, while the company’s ESG performance is evaluated by using TESG sustainability scores with respect to the performance in ESG for each of the three (E, S, and G) pillars, with the score for the degree of information disclosure for each pillar excluded, to identify under-performing and over-performing companies in terms of the ESG score. The research investigates whether the disclosure behaviors of companies change with their ESG performance. Empirical findings show that companies with excellent or significantly improved ESG performance tend to use more complex words in their reports. Conversely, companies with lower ESG performance are more likely to reduce the number of complex words used. For companies with excellent or greatly improved ESG performance, the institutional investor ownership ratio and capital expenditure ratio further moderate the association between ESG performance and the use of complex words in the reports. This result supports the notion that companies with superior ESG performance believe that using more complex words provides more specific and objective information, thus optimizing communication effects. Accordingly, this study suggests that researchers should use readability indices, especially the CRIE index, which is commonly adopted by accounting studies, with caution, and that the number of complex words in the report helps stakeholders distinguish companies that are leading or lagging in actual ESG performance.