The ablation morphology and insulation properties of the low density thermal protection material on different combination of thermal protection structure were investigated by quartz lamp ablation experiments. It is shown that the morphology is different with thermal protection structure. The morphology is effected by the temperature gradient for longitudinal direction and in-plane direction of the thermal protection structure. The less temperature gradient， the more heat accumulated on the ablation surface， and the more obvious of the carbonization characteristic. The ablation matching is realized between the low density ablation material and higher density material for the combination of in-plane direction. It is revealed that the ablation efficiency and the thermal protection efficiency is higher. The areal density and ablation morphology can be considered for the design of the thermal protection structure. The high efficiency thermal protection and insulation and lightweight design can be achieved by rational utilization of thermal protection structure.