To improve the mechanical property of 2, 4-dinitroanisole(DNAN)/RDX melt-cast explosives, the effect of functional additives, N-methyl -4-nitroaniline(MNA), Tween 60, tris-(β-chloroethyl)fosfat(CEF)and cellulose acetate butyrate(CAB) on the interfacial binding energy was simulated by molecular dynamics. The powder contact angle method and platinum plate method were used to measure the contact angle and surface tension, and the simulation results were verified by calculating the adhesion work. The experiments of adhesion work were verified from macroscopic and microscopic scales by Brazilian experiments and scanning electron microscopy(SEM), respectively. Results show that the order of change ability of functional additives on DNAN/ RDX interfacial binding energy from high to low is CAB>CEF>Tween 60>MNA, and the experimental results agree well with the numerical simulation ones. Functional additives, CAB, CEF, Tween 60 and MNA can make the tensile strength of DNAN/RDX explosive increase by 58.37%, 47.85%, 29.71% and 5.83%, respectively. With the increase of adhesion work, the fracture mode of grain is changed from transgranular/intergranular mixed fracture to pure transgranular fracture.