A multifunctional rack for preassembling and assembling an automobile wire harness mainly comprises preassembling branching supports, two assembling plates, a support frame and the like. The support frame is of a square frame structure, the preassembling branching supports are uniformly and fixedly mounted at the top of the support frame, and the two assembling plates are mounted on two sides of a long edge of the support frame. Small supports are arranged on two sides of the support frame respectively in an extending manner, and the lower portions of the assembling plates are placed on the small supports. Storage supports for holding storage boxes are arranged outside the small supports in an extending manner and are lower than the small supports. By combining preassembling and assembling tool frames, two independent working procedures are integrated, the working procedures are deceased, and production efficiency is improved. In addition, each multifunctional preassembling and assembling rack correspondingly replaces a preassembling frame and an assembling frame, area occupation is decreased, and layout of a workshop is facilitated.