The invention discloses a drilling grouting run-out alarm device and a use method thereof, and solves the problems that in the prior art, manual patrol is needed for judging whether run-out occurs ornot, so that the detection cost is relatively high and the detection is non-timely. The device has the beneficial effects that the monitoring efficiency is high, and the waste of slurry materials is effectively reduced. The scheme is as follows: the drilling grouting run-out alarm device comprises a photoresistance sensor which can be arranged at a groundwater bursting point, an alarm device, an illumination device which can be arranged at a side part of the photoresistance sensor to assist in illumination, and a controller which is separately connected with the photoresistance sensor and theillumination device; and the photoresistance sensor and the alarm device are arranged in parallel.