Underground gangue sorting and filling system and method

The invention relates to an underground gangue sorting and filling system and method. The system comprises a multi-stage belt conveyer, a toothed roll crusher, a strong vibration grading screen, a selective crushing type coal gangue separator, a spiral grading screen, a double roll crusher, a continuous strong stirrer, a bottom groove belt conveyer and a conveying pump, wherein the toothed roll crusher and the selective crushing type coal gangue separator are used for carrying out primary crushing and selective crushing, and the strong vibration grading screen and the spiral grading screen are used for screening in two stages; the screened coal is conveyed into a coal bunker through the bottom groove conveyer; and the screened gangue is finely crushed and then conveyed into the continuous strong stirrer to be stirred with water to form thick materials, and the thick materials are conveyed to the underground goaf to be filled through the conveying pump. The system can realize acquisition operation under the complex conditions of buildings, water bodies, railways and the like, improves the recovery rate of the coal, simultaneously reduces the cost of exploitation of the gangue, aboveground separation of the coal gangue and the like, reduces the floor space of the gangue, and reduces the geological disasters such as spontaneous combustion, acid rain and the like caused by stacking the gangue on the ground.