Abstract: In order to predict the debris distribution in tank quantificationally by initial condition before explosively formed penetrator (EFP) attacks a target, so as to optimize and upgrade the target attack strategy, by adopting numerical simulation verified by experimental data was adopted, behind-armor debris (BAD) formed by EFP penetrating steel target was investigated, the relationship between the amount of BAD and disperse angle was analyzed, the connection between the above-mentioned relation and impact velocity (1700～1900 m/s), thickness of target (30～70 mm), the source of debris (EFP or target) was built. Results indicate that debris distribution could be predicted by initial condition quantificationally and credibly, accumulated amount of BAD generated by EFP and target increases in the manner of Weibull distribution as disperse angle increases.