We investigated the evolution of surface microstructures created on single crystal silicon wafers by the cumulative Nd ∶YAG nanosecond laser pulses (wavelength 1064 nm ) in different atmospheres (N2, air and vacuum). Micropore structure and the fracture lines are formed after irradiation of a few laser pulses,compared with ripple structures created by laser pulses of wavelengths of 532 and 355 nm. The fracture line structure is different for (111) and (100) silicon. The fracture lines have 60°and 120° intersections for (111) silicon. For (100)-oriented silicon wafers, two sets of fracture lines intersect at 90° to form a grid that divides the surface into rectangular blocks with side length of from 15 to 20 μm. We think that phase explosions are responsible for the growth of micropore structure. The fracture lines are mainly due to thermal stress. Finally, We studied the formation of microstructures under different atmospheres, and the results show that it is closely related to the etching and growth rate.