Abstract: Given the size limitation of laboratory test equipment, it is necessary to scale the rockfill in laboratory tests. The mechanical properties of rockfill have scale effect obviously, and how to obtain the mechanical properties of rockfill accurately through scaled tests is one of the key concerns in the engineering field. A series of large-scale pressuremeter tests and triaxial tests are conducted, and a method to obtain the equivalent density of rockfill in laboratory tests is proposed. The relationship between pressuremeter modulus and density can be established through the pressuremeter tests, then the equivalent density can be obtained by comparing the pressuremeter modulus in laboratory with that in field. The test results reveal that the pressuremeter modulus of rockfill increases with the density, and the pressuremeter modulus of rockfill varies with different gradations when the density is the same. The mechanical properties of rockfill with different gradations and densities are similar when the pressuremeter modulus is equal, which indicates that the proposed method is effective and feasible. The research results provide strong support for solving the scale effect problems of rockfill and accurate assessment of dam safety.