The present study focuses on the coefficient of earth pressure at rest (K0) of a saturated crushed binary soil mixture. The mixture is artificially mixed by crushed sandstone and mudstone particles according to presupposed weight ratios and particle size distribution curves. The oedometer tests are performed to determine the coefficient K0. From test data, the values of coefficient K0, which range from 0.242 to 0.381, with a mean value of 0.300, are obtained. Just as other mechanical parameters of soils, the K0 value is affected by many factors. The effects of the properties of test specimen and material are discussed on the basis of the test data. Strong negative correlation between the values of K0 and initial dry bulk density of test specimen, one between the values of K0 and median particle size diameter of test material, and one between the values of K0 and gravel content by weight of test material, respectively, are observed from the test data. The mudstone particle content by weight of the mixture may also affect the value of K0. The effects of these factors on the K0 value may exhibit interlocking effect. Higher interlocking effect results in higher shear strength, and therefore results in lower K0 value.