The invention discloses a system for measuring a vehicle distance through a single camera, and a measurement method thereof. The system for measuring the vehicle distance through the single camera comprises a zoom single-camera module, an operation control module and an infrared emission module, the operation control module is respectively connected with the zoom single-camera module and the infrared emission module, the zoom single-camera module shoots a video of front scenes in real time, captures position information of highlight spots from the video and captures the pixel number occupied by the width/height of a license plate, and the operation control module acquires the position information of the highlight spots output by the zoom single-camera module and calculates the vehicle distance according to a geometric relationship and an averaging algorithm. The method combines a camera video processing technology with an infrared control technology, so the measurement reliability of the short vehicle distance is improved, and the system is convenient to use, reduces the cost, and can be widely applied in vehicle active safety auxiliary systems.