A projector and a wavelength-converting element are disclosed. The projector includes an illumination system, a light valve and a lens. The illumination system includes a light source providing an excitation beam, and a wavelength conversion device located at a transmission path of the excitation beam. The wavelength-converting element includes a substrate having a wavelength-converting area, an optical film disposed in the wavelength-converting area of the substrate, and a fluorescent film covering the optical film and converts the excitation beam into a converting beam. The converting beam and the excitation beam constitute an illumination beam. The fluorescent film contains phosphors, wherein the phosphors having a larger particle size are distributed among or above the phosphors having a smaller particle size. The light valve converts the illumination beam into an image beam. The image beam becomes a projection beam after passing through the lens.