Abstract: Using the gridless smooth particle hydrodynamic(SPH) numerical technique of AUTODYN-2D hydrocode,the characteristics of behind armour debris(BAD)cloud originating from normal impact of cylindrical tungsten projectile on a rolled homogeneous armour plate at velocities ranging form 1.5 to (2.5 km/s) are simulated. From the simulations the target hole diameter,cloud frontal velocity,lateral expansion velocity and maximum emission angle of BAD were obtained for several impact velocities. Based on the results of simulations,an analytical model predicting the mass distribution and spatial distribution of BAD cloud was setup. The results of both simulations and model predictions showed a good agreement with the experimental values.