Abstract: FEM was used to study the ablation behavior of Cflake-SiC-B4C composite plate with different Cflake, contents and degrees of orderliness of Cflake, under aerodynamic heating conditions. The results showed that the transient temperature field distribution in the composite plate is affected obviously by ambient temperature, material's composition, relative density and Cflake with different degrees of orderliness. When the mass fraction of Cflake is 65% in the composite and the mass ratio of SiC to B4C is 5:1 in composite matrix, the composite offers high resistance to oxidation, if the basic structured elements of Cflake are arranged orderly and lots of Cflake grow continuously to form parallel big-area C layers which are piled up to form arched structure of the composite. At that time, the composite offers high resistance to oxidation, just like the testing results.