Retractable window shade with multiple shading gradations

A retractable window shade with multiple shading gradations has a guide rail, two shade bodies and two cord assemblies. The guide rail has two one-way arresting mechanisms. The two shade bodies have different opacities and each shade body has a top side mounted on the guide rail and a lower section. The cord assembles are respectively mounted through the one-way arresting mechanism and connected to the lower sections of the of the shade bodies. The cord assemblies are pulled to rise the lower sections of the shade bodies. When the force for pulling one shade body is released, the cords are selectively arrested by the one-way arresting mechanisms to hold the shade body in a proper position. By expanding both of, one of or none of the shade bodies, the retractable window shade provides a proper proportion of shading sunlight with appropriate, comfortable and mild brightness.