Landfill leachate is one of the most complex wastewaters. Anaerobic treatment has environmental benefits such as low sludge production and biogas production. However, studies have been continuing to achieve better reactor performance. In recent years, ultrasound treatment has been used for different purposes. The aim of this study is to determine the ultrasound effects on anaerobic sequencing batch reactors (ASBR) to increase COD removal efficiency and biogas production for landfill leachate. During operation of ASBRs, in biogas production and methane content, there is an increase of 10% and 7% in pretreated leachate, respectively. This increase in reactor performance is directly related to the transition of landfill leachate's organic matter to dissolved phase by ultrasound pretreatment.