The invention relates to an automobile wire harness capable of automatically adjusting the stretching length, include mounting plate. Two supports, harness body, two winding devices and two clamping devices. The mounting plate is provided with two supporting frames, two supporting frames are symmetrically mounted on the left and right sides of the mounting plate, two winding devices are symmetrically mounted on the upper and lower sides of the mounting plate, two clamping devices are symmetrically mounted on the mounting plate, and two clamping devices are symmetrically mounted on the front and rear sides of the mounting plate. The invention can solve the problem that in the installation process of the existing automobile wire harness. The wiring harness is usually exposed outside, the protection effect is poor, easy to be destroyed, resulting in the wiring harness service life greatly shortened, at the same time can not automatically adjust the length of the wiring harness, too long wiring harness piled up outside, and occupies a large amount of space, affecting the use effect, poor use effect, complex operation, installation and disassembly inconvenience and other problems.