A projection apparatus and an illumination system that includes an excitation light source, a beam filter module, a wavelength conversion module and a homogenizing element are provided. The beam filter module includes a light effective region and is disposed on a transmission path of an excitation beam. The wavelength conversion module includes a wavelength conversion region and is disposed on a transmission path of the excitation beam reflected by the light effective region. The wavelength conversion region converts the excitation beam into a conversion beam. The conversion beam from the wavelength conversion module passes through the light effective region and then forms at least one color light. An optical axis of the excitation beam incident on the light effective region and a normal line of the light effective region are respectively not parallel to a central axis of the homogenizing element.