The invention discloses a display panel, a display method thereof and a display device. During display, sub-pixels in a second display area are controlled to perform display according to brightness higher than brightness corresponding to initial grayscale values corresponding to the sub-pixels, which is equivalent to a condition that the brightness of the second display area is appropriately improved, and therefore, brightness difference between a first display area and the second display area is decreased; alternatively, the brightness of sub-pixels in the preset ranges of the first display area which are adjacent to the second display area is decreased, which is equivalent to a condition that the brightness of sub-pixels in the first display area which are adjacent to the boundaries of the second display area is decreased, and therefore, brightness difference between the first display area and the second display area at the boundaries can be decreased; and alternatively, the increaseof the brightness of the second display area and the decrease of the brightness of the sub-pixels in the first display area which are adjacent to the boundaries of the second display are combined, sothat brightness difference between the first display area and the second display area at the boundaries can be decreased.