A positioning assist device, characterized by comprising: a first fixator installed on a front wheel on one side of an automobile; a second fixator installed on a rear wheel on one side of the automobile, the first fixator and the second fixator being located on a same side of the automobile; a first connecting rod connected between the first fixator and the second fixator, wherein a vertical plane, where a center line in a lengthwise direction of the first connecting rod is located, is parallel to a center axis plane of the automobile; a second connecting rod disposed perpendicular to the first connecting rod; a horizontal reference rod installed on the second connecting rod and rotatable about the second connecting rod, wherein a horizontal plane, where the center line in the lengthwise direction of the horizontal reference rod is located, is perpendicular to the horizontal plane where the center line in the lengthwise direction of the first connecting rod is located; and a laser device movably installed on the horizontal reference rod, the laser device being used for emitting laser light downwards to form a laser line on an object located below the laser device, and a horizontal angle of the laser device relative to the first connecting rod being adjustable to be an angle, relative to the center axis plane of the automobile, of an energy receiving and transmitting surface of a radar assembly to be installed when the radar assembly to be installed is installed on one side of the automobile, wherein the horizontal angle of the laser device relative to the first connecting rod is the angle between a direction of the laser line emitted by the laser device and the center line along the lengthwise direction of the first connecting rod in the horizontal plane where the center line along the lengthwise direction of the first connecting rod is located. a first fixator installed on a front wheel on one side of an automobile; a second fixator installed on a rear wheel on one side of the automobile, the first fixator and the second fixator being located on a same side of the automobile; a first connecting rod connected between the first fixator and the second fixator, wherein a vertical plane, where a center line in a lengthwise direction of the first connecting rod is located, is parallel to a center axis plane of the automobile; a second connecting rod disposed perpendicular to the first connecting rod; a horizontal reference rod installed on the second connecting rod and rotatable about the second connecting rod, wherein a horizontal plane, where the center line in the lengthwise direction of the horizontal reference rod is located, is perpendicular to the horizontal plane where the center line in the lengthwise direction of the first connecting rod is located; and a laser device movably installed on the horizontal reference rod, the laser device being used for emitting laser light downwards to form a laser line on an object located below the laser device, and a horizontal angle of the laser device relative to the first connecting rod being adjustable to be an angle, relative to the center axis plane of the automobile, of an energy receiving and transmitting surface of a radar assembly to be installed when the radar assembly to be installed is installed on one side of the automobile, wherein the horizontal angle of the laser device relative to the first connecting rod is the angle between a direction of the laser line emitted by the laser device and the center line along the lengthwise direction of the first connecting rod in the horizontal plane where the center line along the lengthwise direction of the first connecting rod is located.