A projector includes an image beam generator and a projecting lens. The projecting lens includes a relay system and a projection system. The relay system has a focusing set and a converging set, and the projection system has a projection lens group and a reflector. The image beam generator generates an image beam, and emits it to the projecting lens, and the image beam emits through the focusing set, the converging set, and the projection lens group in sequence, and then is reflected by the reflector to enter the projection lens group again. After leaving the projection lens group the image beam emits through a lens of the converging set, and then is projected onto a screen.