Abstract: Crystalline silicon was etched by low-pressure water-jet assisted laser etching technique. The effects of laser pulse width, frequency, input current and water-jet velocity on the machined surface were analyzed by orthogonal experiment and the ultimate optimum process parameters were obtained. The results show that the ultimate optimum process parameters were listed as follows: the low-pressure water-jet velocity of 24 m·s-1, the laser pulse width of 1.1 ms, the frequency of 40 Hz and the current of 180 A; When machined with this process, the cross-sectional taper, surface roughness and cross-sectional depth of the notch were 1.2°, 2.63 μm and 1.88 mm respectively, and the notch surface quality was relatively good without edge burst, slag, recast layer and other defects.