The overall technological design of the safe landfill site is illustrated through a hazardous waste safe landfill site project, including the entire process of waste landfill disposal, pretreatment system, landfill structure, anti-seepage system, final cover of landfill site, environmental monitoring, etc. Some key points of the waste landfill site design process are discussed in conjunction with the actual design. Analysis shows that in the coastal soft soil area, the semi-rigid structure which adopts the double lining horizontal seepage control and vertical anti-seepage, can achieve the purpose of protecting the environment.