This invention “the vehicles displace examine know the method” its method are mainly including it are mainly a phantom identification disposal procedure, this phantom identification processing regulation series including the following step: The phantom picks up the step: Picks up the phantom picture material using the photograph unit; Vehicle route identification step: Carries on the analysis the phantom picture material, sets at the traffic lane hairs breadth differentiates, and using the conic section fitting equation, vehicle of route connection the fragment, makes dispatches a vehicle the route forecast model; Obtains the vehicle route forecast model using the above step, but may supply to make the vehicles displacement to examine the knowledge, and provides caution; This vehicles displacement examines the knowledge to install it is mainly is uses including a photograph unit to pick up the path phantom information; As soon as operates the platform is photographs the unit to pick up the path phantom information to analyze, and judges the present vehicles and the path the relative relations; A signal output unit using the optical fiber, the ocular change, or the sound achieves effect of the caution; Because of the above structure and step, when the vehicles travel is not normal, is may send out the danger signal to prompt the driver to pay attention, achieves effect of the early warning.