A headlight for vehicles, including an image light source, a lens module, a lens cover, and a driving device, is provided. The lens module includes a lens assembly and an aperture. The lens assembly is disposed at downstream of an optical path of the image light source. The aperture includes a base and a movable mechanical member. The aperture is disposed at the downstream of the optical path of the image light source. The lens cover is disposed at downstream of an optical path of the aperture. The driving device is connected to the aperture. The driving device includes a power source and a linkage member connected to the movable mechanical member. The lens module includes at least two aperture values, and the aperture values are both not greater than 2.0.