Abstract: To deeply understand the influence of intermediate crack inclination angle on crack propagation and coalescence in fractured limestone, uniaxial compression tests were carried out on limestone specimens with prefabricated cracks.The strain field evolution diagram of the failure process of the specimens was obtained using the 3D digital image correlation technology(3D-DIC technology).The strain field in combination with the crack propagation diagram was used to analyze the entire failure process of the limestone specimens.The test results show that the evolution process of the principal strain field is an expansion process of the high-strain region, which is in good agreement with the crack initiation, propagation and penetration processes.With the increase of the intermediate crack inclination angle, the stress concentration area on the middle of the crack will transfer to the two ends of the crack, while the stress concentration area on the parallel crack will transfer from the end of the crack to the middle.Meanwhile, the coalescing crack type between the parallel the intermediate crack does not change with the inclination angle of the intermediate cracks, remaining as tensile connection cracks.The failure of specimen is mostly splitting or tensile fracture, which is almost not influenced by change of the inclination angle of the intermediate crack.The research methods and results have certain reference value for studying the stability of engineering surrounding rock under the geological conditions of layered rock mass.