An earth system model is the important software for researching climate changes and modeling the earth system. Chinese Academy of Sciences-Earth System Model (CAS-ESM) is the high-performance computing software for earth system simulation developed by Institute of Atmospheric Physics (IAP), CAS. Currently, IAP has released CAS-ESM 2.0, while simulation performance is always one of the critical factors restricting its development. To evaluate and analyze the performance of CAS-ESM 2.0, we install CAS-ESM 2.0 to two high-performance computing platforms, “Yuan” and “Earth System Numerical Simulation Device”, for coupled numerical simulation. The experiment results show that CAS-ESM 2.0 has different performances affected by these two platforms; the atmosphere model has the highest proportion of running time, exceeding the sum of other component models; some component models perform poorly in scalability. Further analysis reveals that the atmosphere model is mainly restrained by ineffective communication. Future research and development of CAS-ESM 2.0 will focus on cross-platform optimization, atmosphere model upgrading, parallel algorithm improvement, and scalability of component models.