Abstract: By using a Rock Failure Process Analysis code (RFPA 2D), slip failure process and associated seismicity in rock masses are numerically studied.The slipping rock mass seems to be of brittle and heterogeneous materials.The simulation result reproduced the whole process from deformation to failure leading to instability inducing seismicity in slipping rock masses and associated acoustic emissions.It shows that shear plane is the main feature of the slip failure mode.The shear plane as it initiated on the one termination of the crack, extends to the center and then to another termination.Finally, a macro scopic shear fault plane is observed.