Abstract: The high-enthalpy ICP wind tunnel is one of the most reliable ground test facilities to test the thermal protection material for space vehicles. For good understanding the flow field, flow parameters need to be known. Due to high temperature nonequilibrium effects, the life of the thermal protection material can be directly influenced by the density of atom O. Therefore, the knowledge of the O density becomes important. The two-photon absorption laser-induced fluorescence (TALIF) technology is a good way to measure atom O. In this paper, the atom O fluorescent signal has been measured based on TALIF in a pure high-enthalpy flow field. To obtain information in a broader region, the laser beam is transformed into a plane with 80 mm width. A clear image of the object with a distance of 1.2 meters from the lens has been got when lens and ICCD parameters are properly set. After the analysis of fluorescent images, the experimental result shows that there is an obvious bow shock wave in front of the model in the supersonic flow field. The concentration of atom O exhibits a maximum value in the area of 30 to 50mm away from the head in the subsonic flow field, and decreases near the surface. These phenomena are consistent with expected result, so the method can be applied to flow parameters measurement in the future.