An illumination system including a plurality of first light emitting elements, a wavelength-converting unit, a first reflector and a second reflector is provided. The first light emitting elements respectively emit a plurality of exciting beams. The wavelength-converting unit is disposed on transmission paths of the exciting beams and converts the exciting beams into a first color light beam. The first reflector is disposed on the transmission paths of the exciting beams, and disposed between the first light emitting elements and the wavelength-converting unit. The first reflector has a hole. The exciting beams from the first light emitting elements are reflected by the first reflector. The second reflector reflects the exciting beams, reflected by the first reflector, to the wavelength-converting unit. The exciting beam reflected by the second reflector is transmitted to the wavelength-converting unit through the hole. A projection apparatus is also provided.