Abstract: Extrusion-cast explosive (ECX) is a new type of composite explosive with high energy and low vulnerability. It can be expected that for ECX wide applications will be found in warhead of high performance weapons. In this work, four ECX with HMX were designed. Cylinder expansion tests of explosives with diameter 25 mm and 50 mm were used to identify the power of ECX formulations with energetic and inert plasticizer. It was found that energetic plasticizer FM-1 had great contribution to the energy of ECX. That is, with the same percentage of HMX (88%), the specific energy of ECX-05 with energetic plasticizer was 22%~23% higher than that of ECX-02 with inert plasticizer, and was better than that of the same type ECX (EX-08-EL) produced abroad. The ability of accelerating metal was close to that of LX-14, i. e., pressed PBX with 95.5% HMX.