The electric x ray collimator is convenient for long-distance control. It is a suitable beam limiter for mobile X-ray machines. The structure of the electric x ray collimator is basically the same as that of the manual East limiter, except that the moving power of the shield is provided by a small motor. The irradiation field can be adjusted to the required size by controlling the motor’s reverse rotation and operation time. In general, micro DC motor is used in the motor, and a limit switch is set at the closing and maximum opening position to automatically limit the position. The movement is sensitive and easy to control. The electric beam limiter for perspective needs to adjust the size of the irradiation field at any time without the indication of the irradiation field and the light indication. However, the electric beam limiter, which is also used for fluoroscopy of photography, should be equipped with illumination field display and light indication system. Electric x ray collimator is a convenient type of beam limiter for photography and perspective.