The present invention discloses an image detection system of a vehicle for detecting at least one target object around a vehicle, and further detecting a distance between the at least one target object and the vehicle. The image detection system of the vehicle at least includes a light source unit, an image capturing unit and an alarm unit. The present invention primarily employs a laser beam incident onto the target object to form at least one optical pattern, and variation of the optical pattern and a motion object detection are collocated to effectively calculate the distance between the target object and the vehicle, thereby achieving an advantage of alarming and alerting a driver to safety of driving.