A vehicle detecting system, a vehicle detecting method adapted for a vehicle, and a computer-readable storage medium encoded with a computer program are disclosed. The system controls two cameras to capture images in the front of the vehicle and at the back of the vehicle respectively, according to a speed and a direction of the vehicle. The system further determines whether or not two images from each camera are the same, if the two images from each camera are different, the vehicle is in a dangerous driving condition, and when times of the dangerous driving condition within a preset time period reaches a preset value, the system outputs a warning to prompt a driver.