Cooling systems consume a significant amount of energy to ensure the reliable operation of data centers. To help data centers achieve carbon neutrality and fully utilize the energy-saving potential of the cooling system

the energy efficiency of data center cooling systems should be evaluated. Many evaluation indexes of these cooling systems are used in the industry. In this study

the energy efficiency evaluation indexes of data center cooling systems presented in the current standards and literature are investigated

and the related indexes are explored as follows: electric energy utilization efficiency and related indexes of derivative cooling systems

performance indexes of data center cooling systems

and performance indexes of data center cold source equipment. The calculation methods and components of different indexes are introduced

and the advantages and disadvantages of each index are analyzed. Comparative experiments reveal that the power usage effectiveness(PUE) and related derivative indexes of the cooling systems cannot accurately reflect the technical level of the operation and maintenance of the data center. For the energy efficiency evaluation of the actual data center cooling systems

the annual general coefficient of performance(GCOPA) is applicable. For the annual operation index of chillers in Chinese data centers

the annual coefficient of performance(ACOP) is applicable.