The processing effect using water-jet guided laser micromachining technology is determined by the accurate coupling of focused laser and high speed water-jet. In order to realize the effective coupling, based on the analysis and calculation, a coupling unit with special structures was designed. The maximum angle of incidence was researched, which determined whether the total reflection occurred when laser transported in the water-jet. By the aid of fluid dynamical simulation, the coupling unit with uniform distribution of inner-cavity fluid field was designed. The attenuation of laser energy in water-jet fiber was investigated. Using appropriate laser wavelength, pulse energy and filtered and de-ionized water, energy attenuation in fiber was reduced. Experimental results showed that applying this coupling technology, perfect water-jet guided laser micromachining can be achieved.