Methane (CH₄) as the second most important greenhouse gas in terrestrial ecosystems after carbon dioxide (CO₂) has received extensive attention in the context of global warming. With the same quantity (number of moles) of greenhouse gas, the greenhouse effect of CH₄ in 100 years is 28 to 34 times that of CO₂, and atmospheric CH₄ is responsible for approximately 20% to 30% of global warming. Reports of a discrepancy between emissions-based estimates and satellite-based estimates of CH₄ sources in tropical forests have generated interest in tree surfaces as a neglected source. Numerous studies in recent years have also proved that trees are an important source and sink of forest CH₄ budget. By review in published literatures, this paper comprehensively analyzed the source, flux size, influencing factors of CH₄ in tree stems and its impact on terrestrial carbon budget. We found that: ① CH₄ released by the stems was produced in the soil or in the heartwood of the tree, and then diffused through the stems into the air.② The flux range of stems CH₄ was from(-37.5±18.75) to (16 937.50±6 812.50) μmol/(m²·h).③ The CH₄ flux on the surface of the stems had a large spatiotemporal difference, which mainly comes from the species, age, tissue type, site characteristics and environmental conditions. ④ The CH₄ released from forest wetland (or woody swamp) might be underestimated, while the CH₄ absorption from dryland or alpine forests might be overestimated, without considering the CH₄ flux from the stems. As a new member of the terrestrial carbon cycle, tree-stems methane should be given sufficient attention, which was of great significance for predicting future global climate change.