Abstract：The traditional oedometer can meet the basic engineering demand. But it has shortage in researching on the soft clay soil. By modifying the traditional oedometer，the osmotic oedometer is developed which has some new functions and merits as following：It has good watertight behavior and can capture water during consolidation of soil specimen. By controlling the drainage condition through the triple valve，not only the single drainage test can be done and the pore water pressure on the bottom can be measured，but also the double drainage test can be conducted. The consolidation tests and permeability tests can be carried out at the same time，and the permeability characteristics of the soil specimen under different load can be studied.
