To satisfy the requirement of large telescope, a large aperture focal plane shutter with aperture size of φ200 mm was researched and designed, which could be started and stopped in a relative short time with precise position. Moreover, the blades could open and close at the same time at any orientation. Timing-belts and stepper motors were adopted as the drive mechanism. Velocity and position of the stepper motors were controlled by the pulse generated by Digital Signal Processor (DSP). Exponential curve is applied to control the velocity of the stepper motors to make the shutter start and stop in a short time. The closing/open time of shutter is 0.2 s, which meets the performance requirements of large telescope properly.