A 355 nm NdYVO4 nanosecond laser with output power of 8 W and a 1030 nm femtosecond laser with output power of 3 W are used for etching the single-crystal silicon. The effects of laser ablation parameters including laser fluence, pulse width spot overlap rate, and processing times on the processing accuracy and quality are investigated and analyzed. The heating effect of femtosecond laser is less than ultravialet nanosecond laser, and nanometer fringes are generated with the laser pulse of femtosecond level, but many cracks appear for the superposition of nanometer fringes as the processing times increases. The experimental results indicate that the advantage of femtosecond laser processing is not absolute, and relatively cheap ultraviolet nanosecond laser may be more suitable for the cases where plenty of materials need to be removed.