In order to improve the coupling effect of focused laser and waterjet fiber,a new coupling system consisting of an accurate coupling alignment system and a special coupling unit was designed,and a special coupling alignment method also was put forward.Before laser arrives at water-jet fiber,it passes through air,glasses and water,so a laser burning method was used to determine the distance between focus lens and nozzle hole based on calculating result.The max angle of laser incidence was researched for full reflection.After fluid simulation,the coupling unit was designed to make the fluid field in the chamber symmetrcally and form a high quality water-jet fiber with diameter of 0.12 mm.The attenuation of laser energy in water-jet fiber was investigated and the energy attenuation in fiber was reduced applying appropriate laser wavelength,pulse energy and filtered and deionized water.The experimental results indicate that a 100 mm long water-jet fiber is formed in this paper,and an 0.12 mm wide slot without nearly crack and heat affected is cut in 0.2 mm thick Si wafer at the speed of 2 mm/s,which shows proposed coupling technology can meet the requirements for water-jet guided laser micromachining perfectly.