The invention discloses a micro-laser beam precision machining optical device, and relates to a precision machining device. The invention provides the micro-laser beam precision machining optical device for laser precision machining, which is provided with visible light coaxial positioning indication and can conveniently realize direct coupling of diffraction-free beams and nozzle micropores. Themicro-laser beam precision machining optical device is provided with a laser, a visible light source, a flat mirror, a beam expanding collimator, an axicon, an optical window, a pressure fluid chamber and nozzle micropores, wherein the flat mirror is positioned in front of the laser and the visible light source; laser beams emitted by the laser are coupled with beams of the visible light source through the flat mirror; the beam expanding collimator is positioned in front of the flat mirror; the axicon is positioned in front of the beam expanding collimator; the pressure fluid chamber is positioned in front of the axicon; the optical window is arranged on the top of the pressure fluid chamber; the bottom of the pressure fluid chamber is provided with the nozzle micropores; and the beams coupled through the flat mirror are coaxial with the beam expanding collimator, the axicon, the optical window and the nozzle micropores.