According to traditional entry model theories, suitable entry model can be chosen by foreign banks through the comparison of cost and revenue. But these theories ignore the impact of entry timing to entry model selection. In this article, real option method is adopted. The conclusion is as following, when uncertainty is larger, partial invest will be preferred; the larger the first-mover advantage, the more possible to implement partial invest; if the investment become more irreversible, full investment is more possible to be carried out. According to the conclusion, this article analyzes the history, current situation and the future of foreign banks into China