Disclosed are an X-ray imaging system and a positioning method of the same that automatically measure a relative positional relationship between devices. According to an aspect, an X-ray imaging system may include: a movable imaging device having a sensor; one or more beacons; a controller configured to analyze position information recognized by the sensor, to compare a relative position between the imaging device and the one or more beacons and to determine a position of the imaging device based on a positional error; and a drive device configured to move the imaging device to the position determined by the controller.