This invention is method and the equipment the one detection distance between vehicles, is applies on an automobile, after using a phantom to pick up the unit picks up the phantom material, by a processor from this phantom material in defines a target sector, analyzes in again this target sector whether to have object of the too close this vehicle, if has, then the processor actuates a caution unit to issue the warning, informs the driver to have the object close this vehicle; Takes advantage of the exemption to carry on the analysis in view of the phantom material entire picture, only analyzes in the target sector whether to have the object too close automobile then, not only so reduced the time which and the burden the processor operates increases the detection speed, and enhanced the accuracy, is not sent the misoperation the caution unit or acts excessively.