Abstract: There exist immense combustion and explosion hazards in propellant, explosive and ammunition enterprises. Therefore, it is of much significance to evaluate the hidden danger of serious accidents in such enterprises. The paper points out a way of establishing a mathematical model for the quantitative evaluation according to principles of system safety engineering, and an evaluation equation is proposed. The meanings and methods of calculation for various factors are discussed. The degree of actual hazard (DAH) for dangerous sources, H, is determined by the following factors, namely: the hazard index of propellants and explosives, WB; the intrinsic danger of the system, B; the coefficient reflecting uncontrolled aspects involving hidden danger, K; and the degree of seriousness of damage, C, of buildings and installations located of insufficient safety distances away from the system that might be endangered by explosion accidents of dangerous sources. Classification of the hazards from dangerous sources and grading of suggested improvements and reorganizations can thus be judged according to the results evaluation.