Abstract: Electrostatic force is served as feedback in closed-loop operating mode to improve the linear character of micromachining capacitive accelerometer. Its function in open-loop operating mode of capacitive accelerometer was analyzed in this paper. The derived equations which describe bias related sensitivity are in well agreement with experimental results. Based on this technology, an accelerometer originally used in range of ±1 g was successfully used in range of ±0.01 g with non linearity less than 0.2%.