The present invention provides a quantum dot display panel, a quantum dot display device, and a preparation method thereof. The quantum dot display panel includes an array substrate, a color film substrate, and a liquid crystal disposed between the array substrate and the color film substrate, wherein the color film substrate includes a cover plate, a light-cutoff layer, a quantum dot pixel layer, a blocking layer, a reflection layer, a coating layer, a built-in polarizing layer, an isolation unit, and a polyimide (PI) layer.