Abstract: According to the specification recently promulgated, it is required to determine filling criteria of incoherent coarse grain materials on the basis of their relative density. But in the light of the construction of earth rockfill dams at home and abroad, there are a series of problems to be solved in carrying out the requirements stipulated in the specification, such as the testing method of relative density of the coarse materials, the standardization of the method and its theoretical basis, method for determination of the relative density of the materials, method of analysis of practical errors, the confidence level of the representative model of gradation of the materials and some problems in the construction work concerning this material, etc.In this paper problems about continuous grading material as mentioned above are studied.