Unregulated landfill sites largely use natural conditions to fill out the untreated garbage and take over lots of land resources. They not only affect the city environmental sanitation, but also pose significant risks to resident domestic water. Because there are many unregulated landfill sites in Beijing, the needed funds for treating all of them are huge. Therefore, preliminary survey and assessment on the unregulated landfill sites are urgently needed to provide the scientific basis for government decision precedence order and choice of technical treatments. Survey and assessment on unregulated landfill sites have a remarkable difference with traditional geotechnical investigation, especially in the areas of required investigation, prospecting technique, exploration of arrangements, and inspection and testing projects.