本研究採個案研究方法，以兩家大型公股銀行－合作金庫銀行合併農民銀行作為研究個案，以合併前後之財務比率作比較分析，並與本國銀行平均趨勢作比較。蒐集個案銀行合併前後共9年之財務資料，包括資本適足性、資產品質、獲利能力、經營及成長能力、營運規模等相關財務指標。以瞭解合併前後經營績效是否有差異，以及合併後是否善用整體資源，而產生合併綜效。 本研究並探討合併案之會計處理，以本研究個案為例，消滅公司農民銀行之資產負債以公平價值或以帳面價值併入存續公司合作金庫銀行，在不同的會計處理對於合併後財務報表之表達及績效衡量，將產生不同的結果。 研究結果，本研究個案銀行之合併，其合併年度及次年，各項指標均較合併前１年為佳，績效較為顯著。合併2年後與合併前1年比較，放款覆蓋率、獲利能力、員工平均獲利額等則略降，各項成長率較本國銀行平均趨緩。另存款市占率及放款市占率2家銀行合併時超過10%，惟未能持續，合併年度之年底及其後年度均未有再超過10%。 This study uses a case study of two large government-owned bank – Taiwan Cooperative Bank and The Farmers Bank of China. It not only analyzes financial ratios before and after the merger, but also compares with the average trend of the domestic banks. The financial data, including the capital adequacy, asset quality, earning ability, management and growth ability, the scale of operation and other relevant financial indicators, are collected for total 9 years. The subject of this study is to know the difference of operating performance before and after the merger and discuss if the company make good use of overall resources to reach merger synergy. This study also discusses merger accounting treatment. Take this case study for an example, adding assets and liabilities of the target firm (The Farmers Bank of China) to acquiring firm (Taiwan Cooperative Bank) at fair value or book value can shows different results. The case indicate that (a.) the performance in the merger year and the following year is better than that of 1 year prior to the merger; (b.) the loan coverage ratio, profitability and average profit per employee in 2 years after the merger decreased slightly than that of 1 year prior to the merger. Besides, the growth rate is lower than that of domestic banks average; (c.) total market share of deposits and loans are both over 10% in the time of merger. However, the situation is not sustainable. The market shares in the end of the merger year and subsequent years are not more than 10%.