Abstract: The density control of dam material is the key index of filling quality control of core wall of earth-rock dams.At present, gravel soil or granular soil is widely used in high dams core wall materials in southwest China.The traditional pit test method is time-consuming and labor-intensive in testing the compactness of dam material, while the additional mass method is mainly used for the rockfill materials, and it is less used for core wall materials.Therefore, based on the additional mass theory model, this paper proposed a new method to improve the digital gauge board.Firstly, based on the test parameters of each measuring point on the rockfill, an equivalent relationship between compactness and test parameters was established by formula calculation, and a theoretical measuring plate was obtained.Then, two different measuring plates were made by constructing parameter equivalence diagrams.The effectiveness of this method was verified by calculating the compactness of gravel soil core wall and comparing that with the results of pit test method.The proposed method is simple in calculation and flexible in parameter equivalence.Compared with the previous digital measuring board, it has the advantages of easy expansion of the measuring board and wider test range.