Abstract: Cylindrical charge blasting in infinite rock was simplified to the plane strain issues.Based on bilinear kinematic hardening yield theory，the blasting process was simulated by ANSYS/LS-DYNA to investigate the effect of biaxial stress of vertical blasthole on crack evolution.Numerical results show that:Fracture zones are circles under the equal bi-directional in-situ stresses，and cracks area decrease non-linearly with the increasing of in-situ stress，but the crack density increases.The quantitative relationship between compressive stress and crack zone area was given；Fracture zones are ellipses under the unequal bi-directional in-situ stresses.The longest axis of fracture zone coincides with the larger compressive principal stress and the shortest axis of fracture zone coincides with the smaller compressive principal stress.Under the condition of smaller invariable compressive stress，the length of long axis and the area of cracks decrease after increasing with increasing of the larger compressive stress，and the length of short axis decreases always.

Key words: Numerical simulation, In-situ stress, Blasting, Rock mass, ANSYS/LS-DYNA, Crack evolution