This paper describes a new electrostatically driven micromechanical 2 x 2 optical switch which has advantages in terms of its small size and low driving power. Insertion losses, which are important to the fabrication of a low loss switch, are theoretically and experimentally evaluated. Based on the results, the relationship between cross angle and gap length is obtained in order to minimize insertion loss. The switch is demonstrated and its switching performance is examined. Insertion losses of less than 3.1 dB and crosstalk of less than -40 dB were obtained.