Abstract: In this paper, using the transaction data from inter bank to measure enterprise bonds expected default probability by constructed reduced form models, and make regression models to decompose the expected default probability into ratings default probability and market expectations modified default probability, according to this carried on the empirical analysis. The results show that: Macro liquidity and structural changes have important influence on enterprise bonds expected default probability; the decomposed ratings default probability in enterprise bonds expected default probability accounts for about 15%~31%, and the higher credit rating, the longer period will have a higher default probability. This provides a reference for investors to risk management and pricing in enterprise bonds.