The coefficient of earth pressure at rest K0 is particularly important in the calculation of earth pressure of retaining wall. In this paper, the K0 value of sand with different particle sizes and compactions was studied by centrifugal model tests. Firstly, soil samples were prepared by sand pourer, and the designed compactions of sand samples under different types of sand outlets and drop distances were measured by self-made sanding device. Then, through reasonable design of earth pressure measurement model structure, the centrifugal model test was used to simultaneously measure the soil compression and the horizontal earth pressure on the aluminum alloy plate. The variation of the K0 value of sand with different particle sizes and compactions was finally obtained by calculation. The test results showed that, when using the sand pourer to prepare the samples, different types of sand outlets and drop distances should be adopted for different soil samples. In the centrifugal model test on the K0 value of sand, the order of soil settlement was #1 sand > #3 sand > #2 sand, and the settlement of #1 sand and #3 sand was close to each other. For sand with the same particle sizes, the K0 value increased gradually with the increase of the relative compaction of soil sample. For sand with different particle sizes, under the same compaction, the larger the sand particle size is, the smaller the K0 value is.