本文所使用信用風險評價模型為KMV公司用以衡量未上市公司之違約風險的PFM模型(Private Firms Model)，主要的研究標的為美國未上市產險公司。此模型最主要的目的在求出公司的資產市值及資產市值報酬率波動度，並假設資產市值的變動遵循標準幾何布朗運動，因此在產險公司的資產市值小於某值後，該公司即算違約，其中資產市值平均與該值的距離稱為違約距離。而未上市產險公司缺少股價資訊，因此無法用一般的選擇權評價公式求得資產市值及資產市值報酬率波動度，所以先使用可以衡量上市產險公司資產市值的KMV模型(Moody's KMV EDF□)，找出上市公司的資產市值及資產市值報酬率波動度，再找出財務比率與兩者的關係，最後再將這層關係套用到未上市產險公司，如此可以求得未上市產險公司之資產市值及資產市值報酬率波動度。 本文經過實證研究過後，發現套用從1991年到2000年上市產險公司資料中找出的關係，代入2000年的未上市產險公司資料來預測公司於2001年是否違約，其結果發現準確度並不高；接著且再以違約距離和少部份財務變數做為預測模型，代入2001年資料，以預測2002年未上市產險公司的違約與否，其準確率也與先前相近，兩者的解釋能力約都只有六成到七成，雖然如此，還是可以發現違約距離在解釋能力上還是有一定之貢獻，如果可以將違約的樣本群數量□加，應該可以提升預測的準確度。 / This theme is to measure the default probabilities of private P&C firms’ default in the U.S A. The model this paper used is called PFM (Private Firms Model). The asset value and asset volatility could be found by this model, but we must assume that the asset value will follow General Brownian Motion. After finding asset value and asset volatility, the next step is to find the default point. The distance between the expected asset value and the default point is DD (Distance to Default). However, the private P&C firms lack the relative stock information, so the Black-Scholes Option Pricing Model couldn’t be used. In order to find the relationship between the private firms’ asset value and asset volatility, we can use Moody's KMV EDF□ (Expected Default Frequency) credit risk pricing model to measure the public P&C firms’ asset value and its volatility and find the relationship between those and firms’ financial ratios. Using the public firms’ relationship on private firms, the distance to default of the private firms can be found. Through the empirical research, the correct rate of this model on the private P&C firms in the U.S.A is low. Besides, let DD and other financial ratios be the variables to forecast the next year, the correct rate is still low, but we can find that DD’s ability to explain the default probability is 60~70%. Therefore, we can say DD is still the useful variable and if the sample size of default firm can be increase, the correct rate may be promoted.