Abstract: Large-scale experimental installation was established according to the semi-aerobic landfilling theory, and the volume fraction of methane, as well as that of oxygen, in different layers in this semi-aerobic landfill was monitored. The results showed that the ch₄ and O₂ volume fractions in the landfill underlayer were （33.1%） and （1.1%,） respectively; the fractions in the landfill middlelayer were （15.0%） and （4.2%,） respectively; the fractions in the landfill upperlayer were （3.1%） and （12.2%,） respectively. Compared with this, in the anaerobic landfilling structure, the volume fraction of ch₄ in underlayer, middlelayer and upperlayer was respectively （31.5%,）（ 32.6%） and （22.0%.） In semi-aerobic landfilling structure, ch₄ volume fraction declined according to the sequence of underlayer, middlelayer and upperlayer, whereas the O₂ fraction declined according to the sequence of upperlayer, middlelayer and underlayer. The average methane volume fractions in semi-aerobic landfill treatment and anaerobic landfilling treatment were 17.0% and 29.0%, respectively.