Abstract: In smooth pre-splitting blasting, two collinear cracks extending opposite to each other between adjacent holes will first avoid each other and then attract each other, resulting in crack propagation path that often presents hooked or butterfly-shaped loops.Based on the maximum tensile-stress criterion modified by T-stress, this study probed into the crack propagation behavior of two collinear mode Ⅰ cracks extending opposite to each other by using Abaqus and Hypermesh.The numerical results indicated that model size(ratio of model width to height: W/H ), crack length(ratio of initial crack length to circular hole radius: a/r)and pressure distribution of explosive gas on crack surface have a significant effect on crack growth behavior.Deflection occurs during the propagation of mode I crack, which makes the crack propagation path presents hooked loops.The explosive gas on the crack surface reduces the degree of deflection in mode I crack propagation, and makes it more difficult for the crack growth path to show "hooking" phenomenon The crack propagation path is simulated by the method of incremental crack propagation and the results show that the crack propagation path of mode I crack does present hooked loops.The phenomenon of "hooking" of crack propagation path is related to the interaction between the cracks, which can be represented by the crack growth angle θ.