We describe an optical switch based on the stepper motor, which can be used to the pulsed atomic clocks. The switch consists of a two-phase stepper motor with 6 mm diameter and blades with different shapes to switch on and off the light. A universal stepper motor driver chip (TMC260) and a microcontroller (STC12C5A60S2) are used to control the rotation of the motors. The control system is compact. One microcontroller can be used to control multi-motors. The experimental results show that the extinction ratio higher than 100 dB is reached and the optical switches can work normally for a long term.