UNS N08810 material is the highest allowable temperature metal material in ASME Volume 3-D5, due to its excellent high-temperature strength, oxidation resistance, carbide resistance, and high-temperature corrosion resistance, it is widely used in nuclear power and many industrial fields. In the manufacturing and processing process of large-sized parts, large-sized rods are often used as the starting point for manufacturing, therefore, the control of large-sized rod manufacturing process is very critical. For the application of UNS N08810 alloy in nuclear industry, referring to the ASME code, the grain size should be controlled to be below level 5, and the A, B, C, and D class coarse and fine inclusions should not exceed level 1, the B class TiN coarse and fine inclusions should not exceed level 2.5, and the D class TiN coarse and fine inclusions should not exceed level 3. In this study, two specifications of rods with φ75mm and φ100 mm were selected, and UNS N08810 rods in the state of extrusion and heat treatment were manufactured and sampled. According to the ASTM standard, the grain size, microstructure, and mechanical properties were analyzed separately, and the influence of different manufacturing processes on the material's microstructure and properties was studied. Through the study, it was found that the inclusions of both manufacturing processes meet the requirements. For the grain size, the extruded state has relatively fine grains, which do not meet the requirements of the ASME code. The heat-treated state has a more uniform organization and meets the requirements of the ASME code. For the mechanical properties, the room temperature mechanical properties of the rods manufactured by the two manufacturing processes are almost the same.