In order to study the effect of polymers such as polyolefin， polyester， polyurethane and polyether on the mechanical properties of DNAN and its mixed explosives， the physical miscibility of different polymers with DNAN was studied by X-ray testing， in which polymers were microcrystalline wax（WAX）， polyisobutylene（PIB）， polybutylene succinate（PBS）， polyadipic acid hexanediamine（PA） and poly（3，3-di（nitrate ester methyl） oxybutyl）（PBNMO）. The solidification process of the polymer-containing samples was observed by microscopic. The dynamic crystallization characteristics of the samples during solidification were analyzed， and the linear velocity of crystal growth was calculated. Based on the optimized polymer， the influence of polymer content on the mechanical strength of DNAN and its mixed explosives was studied by material testing machine. The mechanical strengthening mechanism of polymer to DNAN and DNAN based explosives was analyzed. The results show that PBS， PA and PBNMO have good mutual solubility with DNAN under the action of hydrogen bonds or π bonds. The addition of fusible polymer makes the solid-liquid interface of DNAN crystals smooth and the solidification linear velocity decreases by more than 54%. Among them， the PBNMO has the most obvious improvement on the crystal morphology and solidification linear velocity of DNAN. PBNMO could significantly improve the mechanical properties of DNAN and its based explosives， and the mechanical strength increases with the increase of polymer content. When the polymer PBNMO content was 2%， the tensile strength and shear strength of DNAN based explosives increase more than 100%. The mechanism study shows that the fusible polymer can improve the mechanical properties of DNAN-based explosives by improving the microstructure of the sample and forming the “reinforced concrete” structure to reduce the internal defects and improve the crack growth resistance.