Abstract: Methane is an important greenhouse gas. According to the estimation of IPCC, the methane emission from rice paddies was about 20% of the total methane e-mission. Studies from China, one of major rice producing countries , showed that the methane emission flux from rice paddies in China varied from 7. 8 to 60mg/m²· h. The methane emission from rice paddies actually consists of two processes, the formation of methane in paddy soils and the release to the atmosphere. Methanogen providing anaerobic condition in water logged paddy (soil Eh value below -200mv) plays a key role for the methane formation. The methane emission from soil to the atmosphere is mostly through rice plants, only small amounts of methane is released across the water-air interface via bobbles or molecular diffusion. Therefore, the methane formation and emission is mainly a biological process. Some physical and chemical conditions of paddy soil, paddy water and atmo Sphere, such as temperature, pH, flooding period and application of organic manure and chemical fertilizer, greatly influence this process. With the understanding of the mechanism of methane emission from rice paddies, the methane emission rate can be reduced along with a good rice production. 

Key words: methane, rice paddy, emission mechanism, emission reduction