Abstract: The 4J29 alloy formed by MIM underwent post-treatment through Hot Isostatic Pressing（HIP）at various temperatures. The study is aimed to explore how HIP temperature influences the microstructure, coefficient thermal expansion and tensile behavior of the 4J29 alloy. The results reveal a gradual increase in alloy density with rising HIP temperature. However, beyond 1 200 ℃, the density enhancement rate decelerates, hardness decreases, and grain size exhibits accelerated growth. The leak rate follows a trend of initial decrease, reaching its minimum at 1 200 ℃, and then increasing. Before 1 200 ℃, the leak rate decreases with temperature, and beyond 1 200 ℃, it gradually rises. The optimum HIP temperature is 1 200 ℃, resulting in the alloy reaching a density of 98.54%, a leak rate of 1.2×10^-9 Pa·(m³/s), hardness of 81.3HRB, an average thermal expansion rate of 2.0×10^-6 m·℃ between 30~200 ℃ and along with a noticeable enhancement in tensile strength and elongation.