The embodiment of the invention discloses a method and device for calculating the number of coverage times of surface elements. The method comprises the steps: carrying out the prestack offset calculation of reflection energy corresponding to each obtained offset in a preset observation system; and calculating the number of offset coverage times of each surface element. According to the embodiment of the invention, the method can directly reflect the quality of the prestack offset effect, and achieves the effective assessment of the offset effect of the observation system.