The invention discloses an automobile tire crack detector, which comprises jacks, bases, a first connecting rod, and a crack detection unit, the interior of each base is of a hollow structure, both the inner side and top of the base are provided with openings, the first connecting rod is connected to the interiors of the bases via the openings, the jacks are arranged on the first connecting rod via the openings, fixing mechanisms are also arranged on the tops of the jacks, racks are arranged on the outsides of the bases, two straight tubes are arranged on the first connecting rod, the straight tubes are provided with detachable fixing devices, the fixing devices are connected to the racks, and the crack detection unit is arranged on the first connecting rod and slidably connected to the first connecting rod. By means of the jacks, the bases and the first connecting rod, a user can manually push and pull the first connecting rod, so that jacks slide on the bases, and thereby the user can conveniently adjust the positions of the jacks. By means of the fixing mechanisms on the tops of the jacks, the user can place the automobile tire crack detector at a reasonable position. By means of the cooperation between the racks on the bases and the fixing devices, the relative siding between the jacks and an automobile can be prevented.