Road milling machines or cold milling machine is a road maintenance and construction machine mainly used for removing asphalt and concrete surfaces quickly and efficient. It can realize the small-area digging and renovation of asphalt concrete pavements, including highways, downtown roads, airports, cargo yards, and parking lots, and can be used for the removal of road bulges, asphalt ripples, overlapping curves, and tracks and for the scuffing of cement roads and the milling of pavement jumps. It can realize the milling along edges and manhole covers. Also it can realize the road crushing function if the optional hydraulic pickaxe is installed and realize the milling of roadside rumble strips if the optional rumble wheel is installed.