Embodiments of the present disclosure relate to a substrate for a curved display panel, the curved display panel, and a curved display device. A substrate for a curved display panel is provided. The curved display panel includes a plurality of opening areas arranged in an array. The substrate includes a first base substrate which is curved; a strip-shaped black matrix positioned on the first base substrate and extending along a direction approximately parallel to a curved edge of the first base substrate; and a blocking portion positioned on the first base substrate. An orthographic projection of the blocking portion on the first base substrate is within an orthographic projection region of the opening area on the first base substrate.