Ceramifiable ethylene-vinyl acetate copolymer（EVA）composite with three dimensional cross-linking structures was prepared by using bis(tertbutylperoxy) diisopropyl benzene (BIPB) as cross-linking agent. The FT-IR spectra and the value of gel content as 99.3% prove that the cross-linking structures are formed. Then the degree of cross-linking in the EVA matrix with silicate glass frits (SGF) and ammonium polyphosphate (APP) as additives was studied. The value of gel content as 98.8% suggests that the SGF and APP show no effect on the cross-linking reaction. Dynamic rheological analysis shows that the cross-linked EVA composite has higher shear viscosity and melt strength than unmodified EVA composite. Thermogravimetric analysis (TGA) results indicate that the cross-linking modification can improve the thermal stability of the composite. The cross-linked EVA composite exhibited a higher T5% degradation temperature (T5% = 329 ℃) than unmodified EVA composite (T5% = 311 ℃). The fire resistance tests show that the flexural strength of ceramics residues of the cross-linked EVA composite increases with the increase of ablation temperature, the flexural strength is 1.94 times that of the unmodified samples at 1000 ℃, and can well support the weight of the residues in the ablation process，which is also shown by SEM analysis that the surface structures of the residues of the cross-linked EVA composite have a more continuous and more compact structure at corresponding temperatures than unmodified samples. Therefore, the cross-linking structures in the matrix improve the fire resistance of the material.