Methane emitted from wetlands contributes significantly to greenhouse effect.Methane emission is resulted from the combined actions of input and decomposition of organic matter and production,transmission and oxidation of CH_4.The most important variables controlling CH_4 flux including temperature,water level,vegetation,and organic matter content,pH,redox potential and properties of soil are discussed The change in future trend of wetland methane emissions is discussed as well.Future research directions are then analyzed.This review provides the basis for prediction of atmospheric methane concentration with the consideration of global climate change and human activities.