The invention discloses a method for monitoring the falling off of a distributing chute of a blast furnace. The method comprises the steps of adopting scanning radar to determine the shape of a chargelevel, specific as follows: a charge level scanning radar unit, a database unit, construction of a chute state recognition knowledge base unit, top charge level shape pattern recognition, etc; if theshape of the charge level is similar to a normal case base, judging that the chute is normal, and enabling the blast furnace to normally work; and if the shape of the charge level is similar to an abnormal case base, judging that the chute works abnormally, and carrying out blast furnace maintenance. According to the technical scheme, whether the distributing chute of the blast furnace falls offor not can be found in the first time according to the abnormal distribution of the charge level; once the distributing chute falling off is recognized by the abnormal charge level, a computer gives an alarm in time, the blast furnace shuts down, the top of the blast furnace is opened for manhole maintenance, a new chute is mounted in time, and therefore the blast furnace loss is significantly reduced.