The weapon equipment system of sytems capability is an important part of the weapon equipment system of sytems. In this paper, the weapon equipment system of sytems capability is described formally, and the character is given. The weapon equipment system of sytems capability spaces is analyzed and the relation between the capabilities is defined from different viewpoints. The weapon equipment system of sytems capability subsystem is built. Based on the singer capability, capability relation and capability system, the weapon equipment system of sytems capability is discussed, which establishes the basis for the study of the weapon equipment system of sytems and the weapon equipment system of sytems capability.