Abstract: The lake wetland is a significant natural source of methane emission，accounting for 4% - 47% of global natural methane emissions. The invasion of alien plants could change the environmental factors in the lake wetlands， and subsequently， cause great changes in methane emission，which have greatly increased the uncertainty of the methane emission predictions in China's wetlands under the background of global changes. Taking the water hyacinth as an example，we synthetically analyzed the impact characteristic of water hyacinth invasion on methane emission from lake wetlands，and importantly stated the effect of the changing environmental and biological factors on the methane emission when water hyacinth invaded lake wetlands. In addition， we analyzed the changes of the methane production， oxidation， and plant transport mechanisms in lake sediments with water hyacinth invasion， which in turn affected the key process of methane emission in lake wetlands. Finally，we propounded some scientific problems of the methane emission when water hyacinth invaded lake wetlands.

Key words: Eichhornia crassipes, methane, greenhouse gas, lake wetland, alien species, the middle and lower reaches of the Yangtze River