TP347HFG heat resistant steel with different solution temperature were characterized by OM, SEM, hardness and tensile strength test, and its microstructure and corresponding properties were investigated as well. Results show that the grain size of TP347HFG heat resistant steel decreases as the solution temperature increases. Their crystalline sizes are evenly distributed with the solution temperature at 1 180 ℃, whereas the crystalline sizes increase and unevenly disperse at 1 210 ℃. The second phase of TP347HFG heat resistant steel, which is mainly NbC, is composed of both large particles and small particles. Small second phase precipitate at the grain boundary at 1 180 ℃ and 1 120 ℃, which can strengthen the grain boundaries. Most part of the second phase precipitate at 1 210 ℃ in the grains with simultaneous occurrence of the Ostwald ripening phenomenon, where the particle distribution of small second phase diminishes while that of larger one increases, and thus bringing the change of corresponding fundamental properties. The values of tensile strength and Rp_0.2 reach their peaks with the solution temperature at 1 120 ℃ and 1 180 ℃. The elongation property of this material improves while its hardness decreases, as the increasing solution temperature.