ABR process has advantages of wide application, strong impact resistance and low operation cost, which is widely used in the treatment field of domestic sewage, pharmaceutical wastewater and printing and dyeing wastewater. Low load start is the key to ABR start; The seeding sludge has a big impact on reactor start-up, and the more special the seeding sludge is, the easier the reactor is to start. During ABR operating the granular sludge generates. The major research directions for ABR will be further broadening the application areas, fillers developing, and the researches on fermentative hydrogen production system and divisional influent system.