Abstract: In order to clarify what requirements of equipment systems should be,a reference model is brought forward,which focuses on the relations between equipment systems and the problems to be solved.By using the formulas of higher-order logic,the paper describes the relations to be satisfied by the military requirements of equipment systems and requirements specification,and the propositions of adequateness and necessity are also included.The necessity of military requirements merits some appreciation so as to avoid the interference of wrong properties.The necessity of requirements specification gives direct responsibilities to the military and technical workers,and helps them to divide the work.Finally,proof obligations are discussed and verified.The analysis shows that the proof obligations are consistent and feasible.