In order to explore the influence of central crack on unconfined compressive strength and failure characteristics of compacted clay samples, Considering the conditions of crack dip β, crack length 2a and test sample thickness H, The unconfined compressive strength test was carried out on the cubic compacted clay specimens with prefabricated center crack, and the failure characteristics of the specimens under different crack dip conditions were analyzed. The test results show that the crack dip, crack length and test sample thickness all have different degrees of weakening effect on elastic modulus and unconfined compressive strength of the specimen. Among them, the weakening effect of the crack length is stronger than the crack dip, and the weakening effect becomes significant when the test sample thickness is only between 2 cm ~ 6 cm. About the failure characteristics of the sample, the crack propagation mode is mainly affected by the crack dip, When β = 0°, the crack tip mainly expands wing crack; when β = 15° ~ 60°, the crack tip mainly produces wing crack and secondary coplanar crack; when β = 75° and 90°, The crack tip mainly produces wing crack and secondary inclined crack, In addition, tensile microcracks are developed in the middle of the prefabricated crack.