The effect of goethite on methane production by anaerobic digestion of organic matter was studied with waste activated sludge and tobacco waste as research objects. The addition of goethite increased digestive gas production rate to 359.4mL/g, which was significantly higher than that in the blank. Goethite contributed to the increase of methane content in mixed gases and reduced the volume fraction of CO₂. Goethite was conducive to the dissolution of organic matter during co-digestion of waste activated sludge and tobacco waste, and cellulose decreases to provide sufficient digestive substrate for methanogenesis Archaea. Goethite was beneficial to acidification metabolism. The maximum yield of volatile fatty acids in goethite group was only 56.2mg/g, which was significantly lower than that in blank. In addition, goethite promoted the synthesis of propionic acid. Goethite promoted the degradation of acetic acid. On the first day of digestion, the degradation rate of acetic acid reached 65.5% in the goethite group, which was higher than 56.6% in the blank. Enzyme activity analysis indicated that goethite promoted the key enzymes of hydrolysis, acidification and methanogenesis. Methanothrix and Methanobacterium are the important microorganisms in methanogenesis stage, and 454high-throughput sequencing showed that goethite increased the relative abundance of Methanothrix and Methanobacterium to 59.6% and 23.5%.