中文摘要：

自1909年穆迪公司建立第一家信用评级机构开始，到目前全球的评级机构达到了约150家，其中比较著名的评级机构包括穆迪公司、标准普尔公司等。这些机构对公开交易的债券进行信用评级，用以评估发行人按时履行债务合约的能力。

英文摘要：

The industry of credit rating is important mechanism to insure credit transactions in many country and regions today. It is important in China also. The paper introduces and compares the three mainly methods using in measuring the credit rating transitions, and suggests interesting avenues for developing the industry of credit rating in our country.