Objective To analyze and compare the effects of structure parameters on synchronous motor ability between the blood vessel and stent after stent implantation by using finite element method and grey correlation theory. Methods The magnesium alloy stent of S closed-loop type was selected, and 9 models of such stents with different materials, numbers of support in circumferential direction, support lengths and initial diameters were established by using SolidWorks, and these stent models were meshed by using HyperMesh. The synchronous motor ability between the blood vessel and stent after stent implantation was simulated by using ABAQUS, and the influencing factors of different structure parameters on bending stiffness were investigated and compared by using grey correlation theory. Results The effect of materials on stent flexibility was obvious. The flexibility of magnesium alloy stent was the best, and the bending stiffness was 0.958 N?(rad?mm)-1; the best flexibility of stents were those with 5-support in circumferential direction, 1.0 mm-support length, and 1.4 mm-initial diameter, and their bending stiffness was 0.853,0.829 and 1.024 N?(rad?mm)-1, respectively. Conclusions The flexibility of magnesium alloy stent is the best, followed by stainless steel stent, and cobalt-chromium stent ranks last. With the increase of support numbers in circumferential direction, support length and initial diameter, the stent flexibility shows the decreasing tendency; the grey correlation analysis shows that the effect of materials on stent flexibility is the most significant, followed by support numbers in circumferential direction and support length, while initial diameter exerts the smallest influence. The analysis of structure parameter effects on stent flexibility will provide more scientific guidance for stent design and development as well as its intervention treatment in clinic.