Laser microjet is a kind of compound energy field processing, which combined laser with microjet processing as well. While processing laser couples with stabilize pressure microjet and transfers internal total reflection until it arrives at workpieces surface, and changes the Gauss energy distribution to flat-topped laser beam, as well as cools and brushes the processing cross section. The stable low flow pressure deionized water jet waveguides cutting laser flexible extension processing focus, to improve the laser energy distribution while removing chips and cooling and enhance the axial processing quality and accuracy, and improves the laser axial processing ability. Talking about the research development of LMJ and the key technologies of LMJ equipment which including the angle of laser total reflect inner microjet, laser quality, laser transverse model, focal points, coupling precision of laser with nozzle and the stable work distance of microjet etc. At the same time, this processing method is introduced which is suitable for controlling the heat of laser processing, enhancing the direction of laser processing, high quality deep holes, slot and seam with large aspect ratio (about 10–100) as well. The object of the processing method gradually includes high value-added occasions of insulating materials, low- k materials, semiconductor, cemented carbide, such as SiC, GaAs, polycrystalline diamond and other photoelectrical materials.