Fast conformation, good shock resistance and good suspensibility of anaerobic granular sludge are the important characteristics of a new anaerobic treatment plant dealing with high concentration organic wastewater. In order to investigate the diversity and functional characteristics of archaea, most important component of granular sludge, total archaeal genomic DNA was extracted from sample. The community structure was studied by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and cloning-sequencing based 16S rDNA. The results showed that archaeal community clones were classified into Methanosaeta, Methanosarcina, Methanobacterium and Methanomethylovorans all four clusters, accounting for 58.2%, 23.6%, 12.7% and 3.6% of the clone library capacity separately, one clone with 1.8% proportion could not be found the most similar strain. The sequences blast results and phylogenetic analysis of archaea showed that clones C10, C11, C13 and C19 had high similarity with the known strains FJ618821, AB479397, AJ244290 and AB447878 separately and their relative taxonomy groups also be found. Methanosaeta and Methanosarcina were the main clusters in archaeal community, so methane production approach was acetic acid-based. Intermediate metabolites VFAs analysis was combined with different metabolic functions comparison, which confirmed the corresponding relationship between archaeal community diversity and its metabolism function.