In order to obtain the second adiabatic characteristic of I pulse adiabatic materials at double pulse motor, and I pulse the second adiabatic device has been designed and two kind of erosion experiments have been done. Experiments and SEM results indicate the carbonized layer could not protect the adiabatic layer from ablation at higher II pulse flow velocity, the II pulse erosion rate is high obviously compare with I pulse of adiabatic materials erosion rate. While the adiabatic layer could not be removed at lower II pulse flow velocity, the carbonized layer could protect the adiabatic layer and the ablation rate of adiabatic layer would be decreased.