A window shade may include a shade, a sliding base, a weight track, a first blocking unit, and two second blocking units. The shade has two mount bars respectively formed at an upper end and a lower end thereof, and the shade is connected to the sliding base and the weight track through the two mount bars. The position of the sliding base is limited by the first blocking unit while the second blocking units are configured to limit the position of the weight track. With the first blocking unit and the two second blocking units, the shade can be replaced easily, and also the structural stability of the window shade is improved.