Since the flexure hinge mainly works by the local deformation, and the stress concentration exists, and the dynamic characteristics of the micromotion stage are influenced by material properties, designing and manufacturing errors, it is difficult to meet the high precision displacement output under variable working conditions. Based on the principle of stress stiffening, a tension adjusting mechanism is designed by using symmetrically arranged elastic flake flexible hinge with chamfering angle to realize the adjustable dynamic characteristics. The cosimulation of COMSOL Multiphysics and MATLAB is used to optimize the parameters of the tension adjustment mechanism so that the adjustment mechanism can maintain the linear adjustment relationship and minimize the stress distribution of the flexible hinge. The results show that the designed micromotion stage can perform highly linear natural frequency adjustment. Compared with the finite element analysis results, the range of frequency adjustment is different by 2.55%, which is within the theoretical design range.