An imaging system includes an image combiner, at least one reflecting mirror, an image generating device, a communication module and a distance sensor. The at least one reflecting mirror is disposed with respect to the image combiner. The image generating device is disposed with respect to the at least one reflecting mirror. When the image generating device displays an image, a light projected by the image generating device is reflected by the at least one reflecting mirror to the image combiner, so as to form a virtual image through the image combiner. The distance sensor senses a distance between an object and the imaging system and transmits the distance to the image generating device through the communication module. When the image generating device determines that the distance is larger than a predetermined threshold, the image generating device adjusts a display size of the image according to the distance.