The necessity of bank capital adequacy regulations is mainly due to demand. According to NM theory with bankruptcy cost and tax, capital adequacy regulations are fully effective only if the capital ratio stipulated by management and optimal capital structure is consistent. Empirical testing indicates that optimum capital structure of every country's banks is not the same; capital ratio and capital return have no co -integrated relations, and mere isn't an optimal capital ratio for all banks.The way that Basel Agreement stipulates a uniform capital ratio of international banks is not fitting.