Credit rating is divided into subject credit rating and bond credit rating. Subject credit rating is the credit rating of an enterprise or economic subject. Bond credit rating is based on the credit rating of valuable bonds issued by enterprises or economic entities. Credit rating is to evaluate the reliability of bond issuers and the bonds they issue to repay the principal and interest on schedule, and to indicate their credit rating.

According to the credit rating standards of credit market and inter-bank bond market formulated by the central bank, credit ratings are divided into long-term bond ratings and short-term bond ratings. The rating of long-term bonds is divided into three grades and nine grades, which are AAA, AA, A, BBB, BB, B, CCC, CC and C from high to low. Except AAA and CCC (inclusive), all credit ratings can be fine-tuned with "+"and "-"symbols, indicating slightly higher or lower; The credit rating of short-term bonds is divided into four levels and six levels, and the symbols from high to low are: A- 1, A-2, A-3, b, c and d, and each credit rating is not fine-tuned.