Abstract: A lethality model based on the methods of volume overlap for the dimension parameters design of hit-to-kill kinetic vehicle against submunition payload was presented. This model can provide effective calculation and analysis of the influence characteristics of impact velocity and hit-point displacement on the dimension parameters of kinetic vehicle. Example simulations show that dimension parameters of kinetic vehicle depend on impact velocity and hit-point displacement, minimum kinetic vehicle mass and minimum diameter decrease with increase of impact velocity and increase with the increase of hit-point displacement; increase of impact velocity and decrease of hit-point displacement both can significantly reduce the minimum mass of kinetic vehicle.