The present disclosure provides a backlight, a display module and a display device. The backlight includes a plastic frame and light guide plate, the plastic frame includes a panel receiving portion, the light guide plate is located below the panel receiving portion, an orthographic projection of the panel receiving portion in a direction perpendicular to a light emitting surface of the light guide plate is overlapped with an orthographic projection of an edge of the light guide plate in the same projection direction, and an angle between a side surface of the panel receiving portion close to a center of the light guide plate and a lower surface of the panel receiving portion adjacent to the light guide plate is less than 90 degrees.