The discovery of subwavelength periodic ripples with similar grating structures is currently mainly associated with femto-/picosecond laser ablation experiments. A nanosecond laser is generally accepted as incapable of etching subwavelength periodic ripples. Recently, the subwavelength periodic ripples on the surface of silica films induced by nanosecond laser pulses have been observed. In this paper, theoretical models have been established to interpret the formation process of subwavelength periodic ripples etched by nanosecond pulsed laser, and some key questions have been discussed. (C) 2015 Elsevier B.V. All rights reserved.