Ball mill gear adopt the automatic oil injection lubrication device, grease injection of gear meshing place to enter. The improved only will automatically nozzle head moved to gear meshing burning, fixed in the tooth hood, and completes the tubing connection. In order to prevent tooth cover vibration on line, and the influence of nozzle head and for oil circuit system had better choose a section hose. Grease in gear into the meshing former timing injection, timely were brought into tooth room extrusion, glued to the tooth surface forming oil film, improve the gear lubrication condition, and can prevent grease splash. This effectively prolong the operating life of the gear, and save the grease.