The technique of producing methane with lignocellulosic biomass as feedstock has been Used worldwide. In the current study, three types of iron oxides, including goethite, hematite, and magnetite, were used to improve methane production from the aquatic plant curly leaf pondweed. In comparison to the control, hydrolysis efficiency of the aquatic plant in reactors with iron oxides was increased from 31.4 +/- 0.1% to a higher level, which varied between 49.1 +/- 4.6 and 74.1 +/- 4.1%, and the accumulated methane production and formation rates were increased significantly. For all reactors with iron oxides, the accumulated methane production increased with increasing dosages. When the dosages of iron oxide were 0.5 and 1.0% (calculated on the basis of the iron contents), reactors with magnetite showed higher promotion effects. However, when the dosage was increased further to 2.0%, no significant difference was found between the reactors with iron oxides.