The invention discloses a suspended spreading machine leveling device and a spreading machine leveling method. The suspended spreading machine leveling device comprises a detector fixing rack and a controller or power system for controlling the rotation speed of a detector. The spreading machine leveling method comprises the following steps: controlling the height of a detector rack or adjusting the angle of a detector or the rotation speed of the detector, thereby controlling the width of a detected road and the distance from different points on the road to a reference line, and furthermore adjusting the spreading thickness, thereby improving the levelness of the road. The detection width of the detector is controlled by controlling the height of the detector rack, or the angle of the detector on the detector rack is directly controlled, the angle tested by an angle sensor is fed back to a control system, and thus angle can participate in calculation on vertical height. As a single non-contact detection device is adopted, the cost can be reduced, mounting can be easily carried out, and high precision can be achieved due to a plenty of test points. In addition, an ultrasonic sensor is mainly used in the market; however, when being used at the same time, a plurality of ultrasonic sensors can be easily affected by environment and interference can be caused, and moreover the plurality of sensors are not easy to mount; by adoption of the suspended spreading machine leveling device, the defects can be effectively overcome.