Abstract: An anaerobic baffled reactor was developed for the treatment of aniline aerofloat wastewater, a refractory flotation regent. Scanning electron microscopy revealed the shape and properties of granule sludge from different compartments. The microbial communities that might have promary functions were further analyzed by applying Miseq high-throughput sequencing approaches. The results showed that the removal efficiency of aniline aerofloat and COD_Cr increased in each stage despite their great fluctuation in the influent. At a hydraulic retention time of 24 h, aniline aerofloat and COD_Cr removal reached 67%-71% and 68%-73% after 100 days′ operation, respectively. A large amount of granular sludge formed in the reactor, and the particles size distribution was reduced in the direction of flow. The sludge was regular, close-grained and not lost. Miseq high-throughput sequencing results showed that Chloroflexi accounted for most of the sequence (24.73% and 33.60%), followed by Firmicutes (24.17% and 20.92%) and Proteobacteria (18.93% and 20.88%) at the phylum levels. At the genus levels, Caldisericum, Leptolinea, Leuconostoc and Bacillus were identified, which meant the reactor had good resistance to impact load and good degradation effect. The study indicated that ABR may be an effective remover of aniline aerofloat.