An illumination system configured to provide an illumination beam and comprising an excitation light source, a beam filter module, a wavelength conversion module and a homogenizing element, wherein the excitation light source is configured to emit an excitation beam; the beam filter module comprises a light effective region and is disposed on a transmission path of the excitation beam from the excitation light source and the beam filter module is disposed obliquely upstream of the homogenizing element, wherein the beam filter module is configured to rotate around a shaft thereof; the wavelength conversion module comprises a wavelength conversion region and is disposed on a transmission path of the excitation beam reflected by the light effective region, and the wavelength conversion region is configured to convert the excitation beam into a conversion beam and reflect the conversion beam, wherein a wavelength of the conversion beam is different from a wavelength of the excitation beam; and the homogenizing element is disposed on a transmission path of the excitation beam passing through the beam filter module, the conversion beam from the wavelength conversion module passes through the light effective region of the beam filter module and then forms at least one color light, and the homogenizing element is disposed on a transmission path of the at least one color light, wherein the homogenizing element is a light integrating rod, and an angle between a normal line of the light effective region and a central axis of the homogenizing element is greater than 0 and smaller than 45 degrees, an optical axis of the excitation beam incident on the light effective region is not parallel to the central axis of the homogenizing element, and the excitation beam and the at least one color light form the illumination beam. the excitation light source is configured to emit an excitation beam; the beam filter module comprises a light effective region and is disposed on a transmission path of the excitation beam from the excitation light source and the beam filter module is disposed obliquely upstream of the homogenizing element, wherein the beam filter module is configured to rotate around a shaft thereof; the wavelength conversion module comprises a wavelength conversion region and is disposed on a transmission path of the excitation beam reflected by the light effective region, and the wavelength conversion region is configured to convert the excitation beam into a conversion beam and reflect the conversion beam, wherein a wavelength of the conversion beam is different from a wavelength of the excitation beam; and the homogenizing element is disposed on a transmission path of the excitation beam passing through the beam filter module, the conversion beam from the wavelength conversion module passes through the light effective region of the beam filter module and then forms at least one color light, and the homogenizing element is disposed on a transmission path of the at least one color light, wherein the homogenizing element is a light integrating rod, and an angle between a normal line of the light effective region and a central axis of the homogenizing element is greater than 0 and smaller than 45 degrees, an optical axis of the excitation beam incident on the light effective region is not parallel to the central axis of the homogenizing element, and the excitation beam and the at least one color light form the illumination beam.