An active disturbance rejection control (ADRC) strategy is developed for extending the travel range of a MEMS electrostatic actuator to a desired level in the presences of external disturbance and noise. Two controller designs are constructed on the actuator. One is a single-loop classic ADRC design, which is able to achieve the travel range of 97% of the full gap between the two plates of the actuator. The other is multi-loop controller design with an ADRC in an inner loop and a PI controller in an outer loop for charge and displacement controls respectively. The multi-loop controller design can drive and stabilize the displacement output of the actuator to 100% of its full gap. Both controller designs are successfully simulated onto a parallel-plate electrostatic actuator model. The simulation results verify the effectiveness of the controllers through extending the travel range of the actuator to the desired values in the presences of noise and disturbance. The controller performances of the classic ADRC is compared with that of the multi-loop control. Frequency-domain analyses proved the stability and robustness of the two ADRC controller designs.