As more supercritical CO2 (S-CO2) power systems are operating around the world, long term operability and reliability of the system will become salient issues in the near future. In this research, the performance degradation of an S-CO2 compressor is investigated experimentally, and degradation models are developed to explain the performance degradation of the S-CO2 compressor at first. The investigated degradation is damaged on the impeller caused by foreign object approximately 3 mm size. The damage caused the shape change of the impeller. From the comparison of the performances of the damaged impeller to the intact impeller, it is confirmed that the performance degradation does not affect the surge margin. The correction model for the degradation of gas compressor performances has a limitation when the pressure ratio was used for measuring the performance. However, it is also shown that the correction model works well if the enthalpy rise is utilized instead of the pressure ratio. This study experimentally shows the possibility that the performance degradation of the S-CO2 compressor can be modeled through a linear model based on enthalpy. Further research is needed to validate the model for wider operating conditions and more severe degraded conditions.