Abstract: Using the finite element analysis software ANSYS10.0 to make the three-axis variable-capacitance micromechanical accelerometer Finite Element Model to analyze the top three natural frequencies and their vibration mode of the accelerometer.The correlation analysis shows that the first and the second vibration mode have effect on X/Y-axis measure precision of the acceleration respectively,but the third vibration mode have much greater effect on Z-axis measure precision.According to the analysis of the accelerometer structure parameters such as width,height,length of flexible shaft and the height and density of the mass block,it may provide a theoretical basis and analysis method for accelerometer anti-vibration or optimal design.