Abstract: In view of insufficient dissolution and poor cathodic protection effect of aluminum alloy sacrificial anode for secondary filter screen and rotary filter screen of condenser in a nuclear power plant, the relevant seawater quality, chemical composition and electrochemical performance of sacrificial anode were analyzed to studied the failure causes of the aluminum alloy sacrificial anode. The results showed that the low content of main alloy element In and high content of impurity element Si were the main reasons for the worsening performance of the anode. It was advised to strictly control the material quality during the procurement of sacrificial anode. The surface quality, chemical composition and electrochemical performance of the sacrificial anode entering the factory should be tested, and the above performance should meet the relevant standards and technical requirements before application.