In recent years, with the extensive application of deep mixing method in reinforcing the soft clay, study on the basic properties of cement-soil has been conducted deeply. In order to improve economic benefits and social benefit of the deep mixing method, this paper focuses on strength and permeability of cement-soil incorporating both lime and fly ash through laboratory experiments. According to the experimental data, the properties of cement lime-fly-ash soil are compared with those of ordinary cement-soil. The results show that cement lime-fly-ash soil is better than ordinary cement-soil. And some valuable conclusions are drawn based on experimental data. Firstly, the fly ash and lime mixed can raise strength remarkably. Secondly, the fly ash and lime mixed can improve impermeability of cement-soil effectually, especially when cement mixing ratio is very low. Thirdly, adding only fly ash into cement-soil can have adverse effects on the impermeability of cement-soil. In addition, the equivalent cement mixing amount of cement lime-fly-ash soil is identified through experimental data. These conclusions are valuable to engineering design and construction.