The deep space impact load is of great significance to the detection of the internal material composition and structural characteristics of small celestial bodies. Therefore, based on considering the characteristics of the variable section of EFP (explosively formed projectile) and the differentiation of the BAD (behind-armor debris),a spatial distribution model for BAD formed by the perforation of variable cross-section EFP through the target was established. Under the condition that the target thickness is 30 mm to 70 mm and the EFP speed is 1 650 m/s to 1 860 m/s, the model can quantitatively predict the relationship between the velocity, mass, quantity and spatial position of each debris in the BAD cloud.The results indicate that the relative velocity increases by a linear function with the increase of the relative spatial position, the relative mass and the relative number increase by a power function with the increase of the relative spatial position.