EVA-based ceramifying composites, a kind of promising materials, can be widely applied in fire protection field, especially fire resistant sheaths for cables. However, the quick decomposition of the matrix has resulted in cracks and even holes in ceramic residues, which has a disastrous impact on the fire resistance of the residues. Here ceramifiable EVA composites were prepared by melt blending with wollastonite, glass frits and OMMT. Influence of OMMT on the pyrolysis behavior of the composites and properties of ceramic residues was investigated. Thermogravimetric analysis showed that the initial degradation temperature of the composite increased by 12℃ and its maximum weight loss rates at the first stage and the second stage decreased by 25% and 36% respectively, when 10 phr OMMT was added. Besides, for samples heated from room temperature to 1000℃, addition of 10 phr OMMT led to a 20% increase in the flexural strength of the residues. XRD showed that an intercalated structure between EVA and OMMT was formed. Therefore, it was concluded that significant improvement in the thermal stability and the flexural strength is a result of the formation of the barrier layer.