Abstract: Anaerobic digestion（AD）is the mainstream process for clean energy utilization of food waste. By constructing a coupled process（AD-MEC）of AD and microbial electrolysis cells（MEC）,the environmental impacts of AD and AD-MEC,which produced methane by treating food waste,were compared based on whole life cycle assessment（LCA）. The environmental impact contribution of each functional unit was analyzed,and an optimization scheme was proposed. The results showed that compared with the traditional AD process,the potential environmental impacts of the new AD-MEC were lower than those of the AD in terms of eutrophication,climate change,water consumption,acidification and primary energy consumption,with reduction ratios of 70.28%,39.53%,92.29%,49.68% and 41.2% respectively. The analysis of the contributing sources revealed that the pretreatment and wastewater treatment units of the coupled AD-MEC process were the main contributors to the environmental impact,with the MEC and AD units having a smaller impact. Based on the result,the coupled AD-MEC was optimized and the effluent from the wastewater treatment unit was reused in the pre-treatment unit. The potential environmental impact of water consumption was further reduced by 61.48%. Therefore,the AD-MEC coupled process for biogas production from food waste has significant economic and ecological value by effectively reducing the environmental impact and resource consumption of the food waste treatment process through the in-depth utilization of the biogas slurry,the purification and quality of the biogas and the reuse of the wastewater.