The invention discloses a wall monitoring method based on infrared ranging. The technical scheme comprises the steps of controlling a marking instrument to be parallel to a straight line Z away from awall, and to translate back and forth according to a planned step length and a program in parallel to the wall, and controlling an unmanned aerial vehicle to follow the marking instrument, to translate back and forth, and to change the flight height before each time of translation, wherein a laser ranger on one side of the unmanned aerial vehicle is used for measuring the distance between the unmanned aerial vehicle and the wall, the unmanned aerial vehicle simultaneously measures the flight height and acquires the horizontal position after translation from the marking instrument, the unmanned aerial vehicle stores the abovementioned data sets, and the upper computer converts the abovementioned data set into a three-dimensional vector diagram, for expressing the flatness of the wall. Themethod and system provided by the invention have the advantages of being wide in application range, high in accuracy and convenient to use.