Display omitted •Properties of fresh leachate were analyzed by eight-month on-site sampling.•AnMBR achieved an average COD removal rate of 98% for fresh leachate.•AnMBR achieved a maximum OLR of 19.27 kg-COD/m3/d at an HRT of 1.5 d.•High abundances of key microbes contributed to the stable operation of AnMBR.•An excessive OLR at HRT of 1 d caused a sharp decline in the abundance of archaea. This study proposed fresh leachate treatment with anaerobic membrane bioreactor (AnMBR) based on the on-site investigation of the characteristics of fresh leachate. Temperature-related profiles of fresh leachate properties, like chemical oxygen demand (COD), were observed. In addition, AnMBR achieved a high COD removal of 98% with a maximum organic loading rate (OLR) of 19.27 kg-COD/m3/d at the shortest hydraulic retention time (HRT) of 1.5 d. The microbial analysis implied that the abundant protein and carbohydrate degraders (e.g., Thermovirga and Petrimonas) as well as syntrophic bacteria, such as Syntrophomonas, ensured the effective adaptation of AnMBR to the reduced HRTs. However, an excessive OLR at 36.55 kg-COD/m3/d at HRT of 1 d resulted in a sharp decrease in key microbes, such as archaea (from 37% to 15%), finally leading to the deterioration of AnMBR. This study provides scientific guidance for treating fresh leachate by AnMBR and its full-scale application for high-strength wastewater.