The construction of urban subway produced a large amount of slurry with hign moisture content. In order to ensure the stability of the excavation face during the construction of the tunnel shield, prevent the spoil from adhering to the shield cutter, a large amount of additives such as water, bentonite, foaming agent are added to the spoil. Therefore, the slurry has the characteristics of uneven particle composition, high moisture content, low permeability and remarkable plastic flow, and its shear strength is almost zero. The transportation and stacking of slurry can cause environmental pollution and damage the ecological environment. To solve this problem, our research team developed a set of mud-water separation test device to carry out research on mud-water separation technology. The Optimal treatment plan for mud-water separation is given by a large number of laboratory tests: when the moisture content of slurry is relatively high, the vacuum negative pressur is firstly used to discharge the free water. When the moisture content drops below the liquid limit, the electroosmosis and the vacuum negative pressure are combined to discharge the bound water, at which time the moisture content in the slurry is close to the plastic limit, thereby achieving slurry hardening. This method has a fast drainage speed and low cost, and has been successfully applied to the Suzhou Metro. It is not only conducive to the resource utilization of slurry, but more importantly, it can effectively protect the ecological environment.