Abstract: The properties of sludge have a significant impact on the effectiveness of pretreatment enhanced anaerobic digestion process. This study compared the changes in sludge properties and gas production efficiency of residual sludge generated by A 2O process and A 22O-MBR process in a practical sewage treatment plant during microwave pretreatment anaerobic digestion process, and examined the changes in archaeal community structure of sludge during pretreatment and anaerobic digestion process. The results showed that the organic matter content of residual sludge from A 2O process was 16% higher than that of A 22O-MBR sludge 4% (66% respectively) 4% and 50 0 SCOD、 Dissolved proteins and polysaccharides are the latter 1 24, 2 02 and 4 84 times, with better biodegradability. Although pretreatment has a better effect on the release of organic matter from A2O-MBR sludge with poor biodegradability, the methane production of A2O-MBR sludge after microwave pretreatment anaerobic digestion is 26% higher than that of the corresponding treated A2O-MBR sludge 1%. There is a significant difference in the archaeal community structure between the two types of residual sludge. The abundance of Methanobacterium and Methanococcus in A2O-MBR sludge is 3 68% and 19 73%. Pre treatment has a relatively small impact on the richness and evenness of archaeal communities, but fluctuates greatly after anaerobic digestion. Different organic components in sludge are important factors causing changes in the structure of archaeal communities.