金融資產透過證券化過程，可提高金融資產流動性及資金使用效率、改善資產負債管理、分散金融資產風險、提高經營績效、降低資金成本、提供更多樣化之投資工具等特色，但其中也具有一些風險性存在。不動產抵押貸款證券化中的風險又以違約風險與提前清償風險尤為甚重。尤其在提前清償風險方面，由於過去的文獻中在計算風險機率時，並未對提前清償時點的房價及可貸成數這兩個要件將影響可再融資金額作考慮，因此有著不客觀的盲點存在。故本研究參考過去的模型導入再融資房貸的這一個重要限制，對違約與提前清償風險作更全面及深入的探討。

The financial institution will increase the financial efficiency and diminish the cost of capital by asset securitization. So we know there are some risks in the process of asset securitization, those include interest risk、default risk、prepay risk 、operation risk and so on. The primary risks in mortgage backed securities are default risk and prepay risk. Especially the side of prepay risk, most of previously research report or thesis do not think about the house price and loan to value at the time of borrower to prepay the unbalance of mortgage. These not only affect the probability of prepayment but also affect the probability of default very much. This thesis adds the constraint into previously model in order to survey overview of prepayment and default. We also to view how huge of the constraint affect the probability.

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