Hazardous wastes can cause great harm to the environment, so the design and the construction of hazardous waste landfill site demand higher standards. Design of impermeable layer is the central issue; construction should guarantee the design requirements with the highest quality. This paper summarized design and construction experience of hazardous wastes landfill sites in China, and the main points of design and construction were given to make hazardous wastes landfill location become really isolated from the biosphere in order to avoid secondary pollution.