Anaerobic digestion is a technology that converts complex organic matter into another form of matter, from which energy can be more easily extracted. The stability and digestion of anaerobic co-digestion with multiple raw materials as substrates is better than the performance of anaerobic mono-digestion. In the past two decades, there has been a large amount of literature on how to improve the performance of methane production in the anaerobic co-digestion process, but few systematic reviews have been conducted. This paper summarizes the factors affecting the development of anaerobic co-digestion. The process parameters, substrate optimization strategy, microbial community, and model application for improving anaerobic co-digestion performance were systematically analyzed. Methane purification technology and policies to support digestion projects are also discussed. At present, the technological process is basically mature, but the interaction between various parameters can be studied in depth. Methane purification technology expands the market for the biogas industry and increases its economic benefits. Policy is the key to promoting process technology and the methane market.