Abstract: Pumped thermal electricity storage（PTES）technology can effectively solve the problem of output fluctuation of new energy power generation system. This paper aims at analyzing the exergy loss and efficiency of the main components in a PTES system based on closed Brayton cycle. It is found that for the compressors and turbines,the compressor in the power generation system has the maximum exergy loss due to its working temperature range crossing the ambient temperature. For the heat exchangers,the exergy efficiency of the low-temperature heat exchanger working near the ambient temperature is the lowest（excluding water-cooled heat exchanger）,and the water-cooled heat exchanger has the maximum exergy loss. The calculated system exergy efficiency is 59.27%. The system exergy efficiency can be improved by raising the efficiencies of the compressors and turbines,and the component efficiency in the power generation system has a greater influence on the system exergy efficiency. Besides,reducing the cooling water temperature or effectively utilizing the heat of the cooling water can optimize the system exergy efficiency.