The invention relates to the technical field of vehicle sensors, in particular to an automobile low-speed driving anti-collision ultrasonic sensor which comprises an aluminum shell with an opening at one end; a piezoelectric wafer which is fixedly arranged at one end, far away from the opening, in the aluminum shell and is tightly attached to the inner wall of the aluminum shell, wherein electric energy and sound energy are mutually converted by the piezoelectric wafer; a control panel which is arranged in the aluminum shell, wherein a gap is formed between the control panel and the piezoelectric wafer, the control panel is electrically connected with the piezoelectric wafer, filler is arranged between the control panel and the piezoelectric wafer, and the filler absorbs sound signals; and a damping material which is loaded in the aluminum shell, wherein the wall thickness of the end, provided with the piezoelectric wafer, of the aluminum shell is 0.2 mm to 0.4 mm. According to the invention, electric energy and sound energy are mutually converted through the piezoelectric wafer, ultrasonic waves are emitted for detection, and the wall thickness of the end, provided with the piezoelectric wafer, of the aluminum shell is 0.2 mm to 0.4 mm, so that the loss of the sound energy is reduced, the vibration frequency of the sound energy is better matched with the vibration frequency of the ultrasonic waves, the detection distance is farther, and collision prevention is better carried out.