The utility model discloses a trailer used in the vehicle detection; the device is characterized in that the device includes a trailer body, a plurality of trailer wheels on both sides of the lower part of the trailer body, and a drive element; the drive element is arranged on the trailer body to drive at least one of the trailer wheels so as to drive the trailer to move. With the structure, the drive element to drive the trailer is arranged on the trailer; therefore, the device can eliminate the relatively large impact on the steel rope by the starting and stopping of the winch in drive in the existing technology; thus the device improves the reliability of the work, simplifies the system configuration, and saves the occupied area of the installation of the drive device.