In order to study the material mechanical properties and constitutive relationship of domestic austenitic S30408 stainless steel bridge deck sandwich panel, uniaxial tensile tests of various stainless steel specimens were carried out at room temperature. Factors such as thickness, orientation and hot air heating and cooling treatment of specimens were considered, a total of 12 groups of 60 tensile specimens were designed, the nominal stress-strain curve and parameters such as initial elastic modulus, yield strength, tensile strength and strain hardening index of stainless steel specimens were obtained, the influence degree of thickness and orientation on mechanical properties of stainless steel specimens were revealed, the nominal stress-strain test curves of the specimens were compared with the classical constitutive models. The results show that stainless steel has obvious nonlinearity and anisotropy; the microscopic morphology is analyzed by SEM, it is determined that the fracture of stainless steel belonged to ductile fracture; 8mm S type specimens have better plasticity than 6mm S type specimens for the stainless steel, the plasticity of 8mm Q type specimens are worse than that of 6mm Q type specimens; the elongation and shrinkage of specimens in the rolling direction of sandwich panel are higher than those in the vertical rolling direction and the oblique 45°; the mechanical properties of stainless steel are obviously changed after high temperature treatment in hot air brazing furnace, yield strength and tensile strength are lower than those of stainless steel, deterioration of plasticity, but the initial modulus of elasticity is almost constant; when , each constitutive models fit well with the test curves, but when , R-O model has a large deviation, Rasmussen model has the best fitting effect, it can be applied to the design and research of stainless steel sandwich panel structure.