This paper investigate the effect on split bond rating and bond yield spread in Korea. We analyzed the effects of the information asymmetry and Credit Rating Agency's reputation on bond yield spread, which is caused by the split bond rating of CRAs. For analysis, We do multivariate analysis, using bond rating and bond yield spread data in Korea 2004 to 2015. The empirical results are as follows. First, we examined whether information asymmetry affected the bond yield spread using multiple linear regression. As a result, the information asymmetry measured by split rating variable were significant, which supports the information asymmetry hypothesis. Additionally we can find bond yield spread is decided by negative credit grade rather than positive credit grade under split rating condition. Next, we examined the relationship between the reputations of CRAs and the bond yield spreads in case of split rating. As a result, the bond yield spread is changed depending on the specific CRAs grade which having conservative rating tendency. This result similar with CRAs reputation analysis using only split rating sample, which supports CRAs reputation hypothesis. Thus, This result suggest information asymmetry caused by split rating and reputation measured by CRA’s rating tendency are affect bond yield spread.