隨著債券市場的發展，如何針對信用風險評價，在債券定價領域變的越來越重要，但目前在這領域的大多數論文都有一個缺點：破產時點的形成不甚合理，在他們的研究中，破產點是外生給定，也因此沒有考慮到股東以及債權人的最佳策略，也因此，在本篇論文中，將以內生性方法決定最適破產時點，其中，許多結果也顯示股東和債權人在面對決定破產時點時，有相當不一樣的表現，除此之外，就公司整體而言，認為只有在公司價值為零時才能破產，這跟目前政府的政策是相同的。 / With the development of the bonds market, the valuation of credit risk becomes the most popular topic in the bond pricing, but most literature in this field falls short in one assumption：the formation of bankruptcy barrier. In their studies, bankruptcy threshold is set exogenously without considering the optimal strategy of stockholders and bondholders. Thus, in my study, the endogeneity is brought into the determination of bankruptcy value and the results do illustrate the different behaviors of stockholders and debtholders to the determination of bankruptcy level. In addition, the choice of the firm as a whole is also taken into consideration and the result is consistent with nowadays policy, that is, declaring bankruptcy until the value of the firm comes to be zero.