Abstract: To reveal the influence of different solid solution temperatures on the microstructure of Invar 36 alloy and explore the optimal process window for obtaining good strength plasticity matching, the average grain size, degree of recrystallization, formation of annealing twins, and changes in grain boundary orientation of Invar 36 alloy hot rolled plates were studied at solution treatment temperatures of 650-900 ℃, and the influence of microstructural characteristics on their mechanical properties was analyzed. The results show that the microstructure of hot rolled Invar 36 alloy was mainly characterized by flattened and elongated fibrous deformation structure, and the recrystallization ratio of the alloy after solid solution treatment increased from less than 20% in the hot rolled state to over 70%. As the solid solution temperature increased from 650 ℃ to 900 ℃, the uniformity of the grain size was greatly improved, with the majority of the grains being equiaxed austenitic structures without distortion. The grain size increased from 21.3 μm to 31.85 μm, and the proportion of high-angle grain boundaries gradually increased. The percentage of annealing twins in the total grain boundaries had increased by 13%. At a solid solution temperature of 750 ℃, the alloy exhibited tensile strength similar to that of the hot rolled state, with a total elongation after fracture of 40%. The toughness of the tensile fracture surface was characterized by tearing, demonstrating good comprehensive mechanical properties.