Abstract: Methane is an important component of carbon output in anaerobic soil. Minor changes to the soil carbon cycle will cause significant changes in the metabolic processes involving methane, which in turn can be markedly affected by exogenous nitrogen input. With increase in anthropogenic nitrogen inputs, exogenous nitrogen becomes an important factor in soil methane production, oxidation, and transmission processes. Methane emissions are regulated by nitrogen availability. Nitrogen inputs can change the background environment and methane emission mechanisms in soil, and consequently influence methane emission fluxes. Research into effects of nitrogen input on CH₄ production and the mechanisms of N effects on oxidation and transport processes in soils are reviewed in this paper. The important findings in the literature are: 1) The effects of nitrogen input on CH₄ fluxes in soils can be positive, negative or neutral, due to the range of effects of added N on methane production, oxidation, and transport processes; 2) The effects of nitrogen input on methane production processes are controlled by methanogenic substrates and methanogenic microbial activities. Nitrogen input provides rich substrates for methane production by increasing soil organic carbon content. The changes in the physical and chemical properties of substrates and vegetation cover make this effect complicated. Nitrogen input can also either promote or inhibit the activity of methanogens, depending on the form of nitrogen supplied; 3) The effects of nitrogen input on methane oxidation processes mainly arise from stimulation or inhibition of the activities of methanotrophs; 4) The effects of nitrogen input on methane transport processes depend mostly on the number of aerenchyma vessels and on transport efficiencies, and the degree of dependence varied greatly in different ecosystems. Overall, the effects of nitrogen input on soil CH₄ production, oxidation, and transport process are complicated and the mechanisms are uncertain. Future research should focus on the effects of nitrogen input on the critical processes determining methane emissions, on investigation of the effects of nitrogen input on microbial community structures, abundance and activities, and on collaborative research in a range of ecosystems. The goal of future research should be to determine the contribution of various ecosystems to global methane emissions at specific levels of nitrogen input.