Abstract: The methanogenic activity of anaerobic sludge before and after the restart of the anaerobic system of leachate was tracked and tested， so as to understand the changes of methanogenic activity of the anaerobic sludge during the storage period and before and after the restart of anaerobic system， to provide a theoretical basis for the rapid restart of anaerobic system after maintenance. Meanwhile， it could also provide reference basis for the selection and optimization of sludge concentration in anaerobic system of leachate in MSW incineration plant. The results showed that when anaerobic sludge was stored without supplementing nutrients during the maintenance period， the methanogenic activity of anaerobic sludge gradually decreased. After taking measures to supplement substrate during storage period， the methanogenic activity of anaerobic sludge increased rapidly. In the six methanogenic activity tests before and after the restart of the anaerobic system， the maximum specific methanogenic activity（measured in VS） of the sludge increased from 47.1 L/（kg·d） in the first test to 343.1 L/（kg·d） in the sixth test. Different sludge concentrations controlled by anaerobic system had different effects on the the maximum specific methanogenic activity rate. The high-concentration sludge test group with a anaerobic sludge concentration（measured in VS） of 35 g /L obtained the highest the maximum specific methanogenic activity rate.