Abstract: An X-ray imaging device and an auxiliary positioning system thereof, include a first display, a second display and a camera. The first display is used for displaying a standard position to a patient. The camera is used for acquiring a position image of the patient, and transmitting the acquired position image to the second display. The second display is used for displaying an overlap graph between the position image of the patient and an automatic exposure control domain, as well as a collimator opening domain of a collimator. With the first display displaying a standard position to a patient, the patient may quickly and intuitively know the optimal position, which reduces the time needed for an operator to give explanations to the patient.