A guide rail for guiding movements of a vehicle window, includes a first structure extending below a beltline of a vehicle door and a second structure extending above the beltline. The second structure includes a bottom wall, a side wall disposed on a first surface of the bottom wall, and an extension part disposed on a second surface of the bottom wall. The second surface is opposite to the first surface. A groove is formed by the bottom wall and the extension part, and has an opening defined by a surface of the extension part and a surface of the bottom wall. A plastic protrusion part is disposed on the surface of the extension part and partially surrounds the groove. The bottom wall is provided with a first opening, two second openings and a third opening. A part of the bottom wall between the two second openings forms a block.