The present disclosure provides a backlight source module including a backplate; a bottom reflective sheet, a light guide plate and an optical sheet which are stacked on the backplate in that order; and a frame disposed at peripheral edges of the backplate for holding the bottom reflective sheet, the light guide plate and the optical sheet on the backplate. The backlight source module further includes a gap adjusting element configured to adjust a gap between the optical sheet and the frame in a direction perpendicular to the backplate.