A new extraction approach for MEMS comb-drive equivalent circuit parameters is presented. The proposed method eliminates the need for fitting and optimization by direct extraction from the measured data and, thus, avoids the nonuniqueness problem associated with fitting algorithms. A silicon-on-insulator-based MEMS comb-drive actuator is designed, fabricated, and measured, and its equivalent circuit is obtained by the proposed procedure. Analytical estimation for the uncertainty in the extracted values due to the discrete nature of the measurement frequency resolution is carried out. Uncertainty in the extracted values of the equivalent motional parameters is well below 0.6% when a 0.1-Hz frequency resolution is used. The method has been used to extract the resonator quality factor at both atmospheric and vacuum operations and can be extended to other types of resonators.