A display panel and a manufacturing method thereof, and a display device are disclosed. The display panel is divided into a display area and a non-display area, and the display panel includes: a display substrate; an upper substrate which is arranged on the display side of the display substrate and cell-assembled with the display substrate; and an adhesive layer which is arranged between the upper substrate and the display substrate, and the display panel further includes a thin film layer which is arranged on the side of the upper substrate away from the display substrate, a region of which corresponding to the non-display area is an opaque area, and a region of which corresponding to the display area is a transparent area. Thus, the structure is simplified, the manufacturing method of the display panel is simplified without side curing, and the cost is also reduced.