In order to improve the safety of linear explosive separation system, the dynamic crack propagation and crack arrest mechanism during the detonation wave propagation of linear explosive separation device were investigated on the basis of the extended finite element method and by creating 2D and 3D models. The results show that the crack propagation path is independent of the initial angle of preset crack. Without considering the loading sequence, the main directions of crack propagation are radial direction and circumferential direction for 2D and 3D models respectively. Once the loading sequence is taken into account, due to the combined effect of the stress wave from different regions, the 3D crack propagates circumferentially and axially but it does not influence the region outside the crackarrest slot either. The method used and results obtained in the study can provide a solution for the design of explosive separation devices.