To improve the laser cut quality of slot array antenna sheet, a new method of laser precision cutting is presented based on vaporization-melt ratio controlled method. The cutting qualities of 6063 aluminum sheets of 0.5 mm in thickness are researched which are cut on a NdYAG pulse laser cutting system, and the effects of vaporization-melt ratio on kerf width, recast layer, kerf sides, and adhering slag are studied as well. Observation on samples of different vaporization-melt ratios (2.62, 3.06, 4.11) shows that high vaporization-melt ratio can improve laser cut quality with decreasing recast layer and increasing the smooth zone of kerf sides. The cut kerfs of 0.2 mm in width on the top, no adhering slag on the bottom, recast layer of 2.03 μm in thickness, and percentage of the smooth zone 40% out of whole thickness are obtained by experiment. The research on vaporization-melt ratio provides the deeper understanding of mechanism of laser cutting, and improves laser cut quality effectively.