Abstract: There is plenty of melting substance on the surface of silicone thermal protection material (TPM) in ablation process, and the melting silicone is shaped into a liquid layer by the flow force. The surface temperature, mass lose, and recession of the TPM are directly affected by this surface flow character. Moreover, the ablation performance and heat insulation performance are indirectly determined by this character. The surface flow character of the silicone TPM is studied regarding two aspects in this paper. The first aspect is the ablation mechanism analysis with the melting silicone defined as a liquid boundary layer. The movement character between the liquid boundary layer and the solid TPM surface is investigated in consideration of the mass injection effect and evaporation phenomenon. The relationship is formulated between the velocity of liquid boundary layer and the flow shear stress, the thickness and dynamic viscosity of the layer. The second aspect is the optical contactless measurement based on 3D vision technique with PIV image processing and optical flow. The study objective is unitary and single movement character of the melting silicone blob on the solid TPM surface. The result shows that, there is strong interactive force between blobs and the velocity of blobs is very different. The mechanism analysis and the 3D vision technique are used to evaluate the velocity of blobs under a test condition. The cold wall heat flux and the recovery enthalpy of the test flow field are, respectively, 1170 kW/m² and 5480 kJ/kg, and the surface temperature of the TPM is 1815 K. The result of ablation mechanism analysis is 26 mm/s, while the optical contactless measurement one is 10 mm/s. The differences between the two results are mainly contributed by the different theoretical assumption, the material parameters, and the measurement region. The ablation mechanism analysis can be used as an engineering calculation method to estimate the test result. The optical contactless measurement can be recognized as a verification tool with the capability of revealing the ablation characteristic of TPM during the test.