Abstract: In order to solve the issue of humanitarian injury posed by unexploded cluster munitions, the concept of fuze harm-reducing system is put forward in this paper. The basic theory of fuze harm-reducing system and its related mathematic description were established. The basic theory indicated that the fundamental function of the fuze harm-reducing system is to reduce the damage degree of unexploded munitions composed of self-destruction, self-neutralisation and self-deactivation. The concept of fuze self-destruction, self-neutralisation and self-deactivation was explained, and the harm-reducing factor, harm-reducing sensitivity factor, harm-reducing degree, damage degree, the safety and reliability degree of harm-reducing system were analyzed in mathematics. Consequently, the design concept of fuze harm-reducing system has come into being with the results of all the analysis.