Abstract: In order to carry out studies of the fracture toughness of the compacted clay, based on a newly developed apparatus, the fracture toughness of the clay is tested in the laboratory. While the rationality of the test methods is verified, researches on the relationships of fracture toughness between dry density, moisture content and shear rates are made. The experiment results show that as the empirical formula, the fracture toughness and the specimen dry density have a positive correlation, and that the fracture toughness will increase with the increase in the dry density of the specimen. The changes in the moisture content are closely related to the test results. When the moisture content of the specimen is between 13% and 17%, with increase in the moisture content, the fracture toughness increases at first and then decreases. There is an optimum moisture content for soil which let the fracture toughness reach a top. When the shear rate is between 05 mm/min and 6 mm/min, the shear rate has a lower influence on the fracture toughness in comparison with the dry density and moisture content. Meanwhile, because the factors such as the soil moisture content, crack depth and the specimen sizes could also have remarkable impacts on the fracture toughness, it is necessary to make studies of the influence factors mentioned above in the future.