The microcapsule particles were successfully prepared by means of in-situ copolymerization of layered double hydroxides (LDHs) with the melamine resin monomers, improving the compatibility of inorganic flame retardant LDH with polymer. The electron beam irradiation was introduced into the process to enhance the mechanical properties and thermostability of the flame retardant composite material. The flame-retardant composites were prepared by incorporating the microcapsule LDH into ethylene vinyl acetate (EVA). The compatibility of microcapsule particles with EVA, combustion and thermal behaviors were detected in sequence through SEM, TG analyses, LOI, UL-94 level and mechanical tests. It was shown that the irradiated EVA/LDH@MF composite had showed the best performances of flame retardancy and mechanical properties due to microencapsulation and irradiation processes. The uniform dispersion of microencapsulated LDH in the EVA matrix was due to the good compatibility of MF shell with EVA keeping the mechanical properties of EVA matrix. The irradiated EVA/LDH@MF with 200 kGy dose achieved a limiting oxygen index (LOI) of 25.5% and a UL-94 V-1 rating. When the dose rate was 100 kGy, the EVA/LDH@MF composite had the best mechanical properties of EVA composites. The microencapsulation of LDH with MF shell incorporated into EVA three-dimensioned network through electron beam irradiation induced crosslinking to enhance mechanical properties.