Abstract The RF switches were fabricated based on microelectromechanical techniques. For good RF performances, the precise control is needed over the contact separation when switch is open and over the contact force when the switch is closed. In this paper, the optical interference technique has been applied to make the accurate measurement of the contact position and the height distribution of the actuators. The shape changes of switches can be observed in original shape and in actuated state. The results were compared with the scan electronic microscope (SEM) measurement.