To investigate the rock slotting performance by pre-mixed abrasive waterjet impact， randomly mixed two-phase smoothed particles are adopted to simulate the abrasive waterjet， the fluid-structure numerical model for rock slotting is established based on the RHT （Riedel Hiermaier Thoma） constitutive model. The changes in relationship between simulated， experimental rock slotting depths and waterjet translational velocity are consistent， and the relationship between simulated and experimental translational velocity of abrasive waterjet is set up. The damage and failure rates of rock elements in the slotting central position and margin are significantly different， which respectively present instantaneous failure and cumulative damage in multiple steps. The impact probability between abrasive particles and rock is related with the concentration of abrasive waterjet， the increasing rate of rock slotting depth is larger when the abrasive concentration is less than 10%. The rock slotting depth goes up and tends to the same with the increasing of abrasive waterjet diameter， and the impact effect of postero-lateral abrasive particles on rock decreases with larger waterjet diameter， and the slotting depths are approximately equal to 6.3 mm when the waterjet diameter is larger than 1.2 mm. With the increasing of waterjet pressure， the rock slotting depth present rising trend generally， but the increasing rate of slotting depth is relatively low when the abrasive waterjet pressure is in range of 15 MPa~35 MPa. The research results can provide important guidance for translational velocity， concentration， pressure and diameter selection of pre-mixed abrasive waterjet.