The company uses the merger policy to increase the company's market share through efforts to create better efficiency and this success can be assessed through financial performance. The purpose of this merger is to encourage Islamic banks to enter the global market and become a catalyst for growth in the Indonesian Islamic economy and are considered to be more efficient in funding, operations and spending. PT Bank Syariah Indonesia Tbk is officially one of the largest Islamic banks in Indonesia through the merger of three Islamic banks from the Association of State- Owned Banks (Himbara), namely PT Bank BRI Syariah (BRIS), PT Bank Syariah Mandiri (BSM) , and PT Bank BNI Sharia (BNIS). This study aims to determine differences in financial performance (Capital, Assets, Earnings and liquidity) of Indonesian Sharia Banks before and after the merger. The variables used in this research are capital adequacy ratio, asset ratio (productive asset quality), earnings ratio (return on assets) and liquidity ratio (financial to deposit ratio). This research is a quantitative research. The population and sample in this study were BNI Syariah, BRI Syariah and BSM before and after the merger with Bank Syariah Indonesia. Quarterly research data from before the 2019-2020 merger and after the 2021-2022 merger. The results of the study are that there is a significant difference in the capital adequacy ratio, return on assets and financial to deposit ratio before and after the merger of Bank Syariah Indonesia, while there is no significant difference in the quality of productive assets before and after the merger with Bank Syariah Indonesia. This research is a quantitative research. The population and sample in this study were BNI Syariah, BRI Syariah and BSM before and after the merger with Bank Syariah Indonesia. Quarterly research data from before the 2019-2020 merger and after the 2021-2022 merger. The results of the study are that there is a significant difference in the capital adequacy ratio, return on assets and financial to deposit ratio before and after the merger of Bank Syariah Indonesia, while there is no significant difference in the quality of productive assets before and after the merger with Bank Syariah Indonesia. This research is a quantitative research. The population and sample in this study were BNI Syariah, BRI Syariah and BSM before and after the merger with Bank Syariah Indonesia. Quarterly research data from before the 2019-2020 merger and after the 2021-2022 merger. The results of the study are that there is a significant difference in the capital adequacy ratio, return on assets and financial to deposit ratio before and after the merger of Bank Syariah Indonesia, while there is no significant difference in the quality of productive assets before and after the merger with Bank Syariah Indonesia.