Objective To analyze the influence of different geometric parameters on flexibility of the commonly used Z-shaped stent-grafts for treating thoracic aortic aneurysm, as well as the primary and secondary order of such influence. Methods The three-dimensional models of the stent-grafts with different strut numbers, wire diameters, crest height, bending radius were established by SolidWorks and imported to ANSYS software for finite element analysis．The 60° rotation of X-axis was applied to the stent-grafts, and the flexibility of the stent-grafts was evaluated according to 3 evaluation parameters (Von Mises stress, reaction force and bending torque)． Results After bending of the stent-grafts, the maximum stress was concentrated on the inside of the bend；reducing the wire diameter, crest height and strut number of the stent-grafts, the flexibility of the stent-grafts would increase; increasing the bending radius， the flexibility of the stent grafts would increase; the effect of the wire diameter and strut number on flexibility of the stent-grafts was stronger than that from the bending radius and crest height． Conclusions The strut number, wire diameter, crest height, bending radius had a significant impact on flexibility of the stent-grafts. The research findings can provide theoretical references for the selection and optimal design of the stent-grafts in clinic, and have a positive influence on reducing the incidence rate of complications such as new entry.