The Global Financial Crisis has brought a severe confidence collapse of customer in financial systems in each country around the world. The analysis exhibits that, after the financial crisis, customer relationship investment of banks has significantly positive effect on relationship performance. However, the ethical sales behavior of bank salesmen does not show significant moderating effect between customer relationship investment and relationship performance of banks. These investigation results have shown that, Taiwanese banks have promptly re-built their customer relationship, but they results have also sent a warning to Taiwanese banks, showing the possibility of repeating the same mistake. This is due to the finding that the effect expected to be brought by the ethical sales behavior of bank salesmen has not been observed.