The tiny differences of physical performance and chemical performance among monocrystal silicons with various crystal surfaces have great effect on micronano processing results, and the behavior characteristics of different monocrystal silicon surfaces under femtosecond laser irradiation are studied by the electron backscatter diffraction (EBSD) technology. The results indicate that the amorphous region and the etching region are formed on the (111) surface of monocrystal silicon when the energy densities of femtosecond lasers are under and above the damage threshold. However, the etching region is formed only on the (111) surface of monocrystal silicon irradiated by femtosecond lasers with different energies. The femtosecond laser is widely used in micronano processing. The study of the behavior characteristics of different crystal surfaces irradiated by femtosecond laser is beneficial to fabricating novel micronano devices.