Abstract: The stiffness of microstructures is an importantparameter for microsensor. This parameter is usually obtained by FEMapproach, and it is difficult to obtain an analytical expression. In thispaper, a kind of microaccelerometer with a complex microstructure is designedand its main-axial stiffness is obtained by force method and energymethod. The theoretical results are compared with those of FEM approachwith good agreement. This methodology is extended to the stiffnessanalysis of microaccelerometer with symmetric and statically indeterminatemicrostructures.