Abstract: The cracks initiation and evolution and distribution patterns in rock failure process are the key to solve the rock failure problems.As a typical rock defect, fissures are closely related to the macroscopic mechanical state and structural damage characteristics of rocks.Using digital image correlation(DIC) and particle flow code(PFC), we study the whole process of fracture of rock specimens with double pre-existing fissures under uniaxial compression.And we obtained the evolution process of the strain and displacement of the entire surface of the observation surface during the fracture of the specimen, as well as the development of sample crack and the number of micro-fracture.The main findings are:①When the load reaches a certain stage, the first micro-cracks appear at both ends of the pre-existing fissures, and its shape is similar to the ellipse.Macro-I-type cracks(wing-type tensile cracks) begin to form.②With the increase of the load, the micro-fracture gathers, the macroscopic type II cracks(shear cracks) begin to form at the ends of the pre-existing fissures, and continue to develop with type I cracks until the specimen is destroyed.③The X, Y direction displacements of the left and right sides of the pre-existing fissures and the upper and lower sides are very different.The displacement in the X direction is positive on the right side of the two pre-existing fissures and negative on the left side; the displacement in the Y direction from the fixed side(lower) to the load side is from the largest to the smallest gradient distribution.