In order to assure the active position for anti-tank missile, the EFP warhead is used to counter active protecting system (APS). Firstly, based on introduction of the principle of APS, the feasibility for EFP to counter APS is demonstrated by the comparison of reaction time. Secondly, the mechanism and characteristics of EFP are also analyzed, the designing gist of EFP is given, and the structure of EFP is designed according to the geometric similarity. At last, the minimum initiation distance of warhead is calculated. The research is laying a foundation for further detailed design of EFP warhead.