Protective fence for ventilation vertical-hole grate

The protective fence comprises stand column bins evenly penetrating through one side of the interior of a mountain body, a grate body is installed on the side, away from the stand column bins, of the interior of the mountain body, fixing blocks are installed at the bottoms of the stand column bins, blocking nets are installed between every two adjacent stand column bins, an access door body is arranged on one blocking net, and the access door body is connected with the stand column bins. A rotating shaft penetrates through the bottom of one end of the stand column bin, and first conical teeth are installed at the end, close to the stand column bin, of the rotating shaft. According to the device, a first bevel gear is in meshed connection with a second bevel gear, and a U-shaped plate is in threaded connection with a lead screw, so that an operator can drive the lead screw to rotate correspondingly by rotating a rotating shaft, and then the U-shaped plate drives an elastic attaching block to be attached to and