Abstract: Landfill has been the most common approach of waste disposal. The waste piles in different climates had different environmental impacts on the surroundings. The characteristics of landfill site should be fully considered and appropriate pollution prevention and remediation measures should be chosen during the treatment process. Taking the typical informal landfill in northern arid areas of China as the research object, through the detection and analysis of the physico-chemical properties, landfill gas composition and microbial community, the characteristics of the waste pile in the arid climates were studied. The results showed that the pile presented the slightly alkaline, with the content of organic matter fluctuating between 5.9%-17.4%, and the moisture between 5.4%-7.8%. The composition of landfill gas was similar to that of quasi aerobic landfill. The organic matter of the waste pile played a decisive role in the production of CH₄, CO₂ and CO. Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes were the dominant bacteria in the landfill. The species abundance was significantly affected by the process of waste degradation and the concentration of organic matter. In the northern arid areas, the amount of landfill leachate was small, and the landfill had minor effect on the surrounding environment. For the waste pile with the organic matter content less than 20% and pH weakly alkaline, the simple covering method could be adopted for differentiated treatment and remediation according to the local conditions when formulating the site closure scheme.