The invention discloses an automatic assembling and disassembling drill rod for a mining drilling machine, a water feeder unit, a device and a construction method. Included are a water feeder support,a hydraulic winch connected with the water feeder support to pull the water feeder support to separate a water feeder from a drill rod, and a pushing unit located between the water feeder support andthe hydraulic winch to push the water feeder support to enable the water feeder to be connected with the drill rod. The water feeder support is movably installed on a water feeder guide rail througha movable plate; and the water feeder guide rail is arranged on a guide rail support. The hydraulic winch is mounted on a guide rail support; a steel wire rope of the hydraulic winch is connected withthe water feeder support; and a pushing unit is arranged on the guide rail support between the water feeder guide rail and the hydraulic winch, and can push the water feeder support to move along thewater feeder guide rail. The technical problems of a power head rear rod adding mode and automatic assembling and disassembling of a medium drill rod and long drill rod in a coal mine underground directional drilling process are solved, instant assembly and disassembly of the water feeder and the drill rod can be achieved, and the drilling efficiency can be effectively improved.