The utility model discloses a mechanical superfine grinding system. The mechanical superfine grinding system comprises an air source, an electric control cabinet, a feeding mechanism, a grinding host, a cyclone separator, a bag-type dust collector and an induced draft fan, wherein the feeding mechanism, the grinding host, the cyclone separator, the bag-type dust collector and the induced draft fan are sequentially in sealing connection with one another by virtue of a pipeline, the air source is sequentially in sealing connection with an air compressor, a level-T filter, an air storage tank, a refrigerated air dryer, a level-A filter and a level-H filter through the pipeline, and high-cleanness compressed air generated by the air source can supply bearing shielding gas and large-particle sealing gas to the grinding host; the electric control cabinet is used for controlling the operation of the whole system; the grinding host comprises an upper host body and a lower host body which are distributed up and down, the upper host body is a grading room, the lower host body is a grinding room, a grading wheel motor and a grading wheel which are directly connected with each other are arranged in the grading chamber, the grading motor is a variable frequency speed regulation motor and can reach stepless speed regulation through a frequency converter, and the speed regulation range is 500-8000 revolutions per minute; a grinding disc is arranged in the grinding room, and a hammer head is mounted on the grinding disc.