An optical printed circuit board includes a substrate, a first cladding layer, a core layer, and a second cladding layer. The first cladding layer is formed on the substrate and defines a receiving groove. The core layer is received in the receiving groove. The second cladding layer is formed on the core layer. The refractive index of the core layer is greater than that of the first cladding layer and that of the second cladding layer. The core layer includes a bottom surface, a first refractive surface, and a second refractive surface. An included angle between the bottom surface and the first refractive surface is about 135 degrees. An included angle between the bottom surface and the second refractive surface is about 135 degrees.