This paper discusses the significance of default rate in credit rating and puts forward the methods for its measurement and its adjustment according to other related factors.

This paper summarizes the latest study of the relationship between external credit assessment and connotative risk information of default rate, declaim rate and transition metrics and difference.

This paper uses Principal Component Analysis to extract and remove the financial indicators which measure the credit risk of enterprises,and gets the principal component factors,then makes use of Logistic regression,the default rate equation is obtained.

And then,combined with the financial indicator,this paper calculates the probability of default for the individual company by the Logit model.

The calculation of probability of default,loss given default and other concerning factors is the key steps to bring Internal Rating Based Approaches into effect.

An evaluation focusing on cross data characters shows that default probability is a suitable indicator to differentiate listed companies\' credit rating.

Forecasting the Default Probability of Single Credit Assets on the Basis of the Logistic Model;

Noisy information,structural model and bank evaluation of default probability;

Based on the reduced form approach and market value recovery,under the assumption of stochastic interest rate,the close form formula for both the pricing of the bond and default probability are obtained.

From the other side, the author analysis the feasibility of efficient breach and the loss from commercial risk transfer of efficient breach in this paper.

The theory of efficient breach is one of the basic theories of common law on the breach of contracts.

This paper points out that the risk parame- ters under IRB,such as PD,LGD and EAD,show procyclical patterns because risk is time varying throughout the economic cycle.