An illumination system, comprising an excitation light source array, a multi-region dichroic device, a color sequence generator, and a wavelength converter, wherein: the excitation light source array is configured to emit a plurality of excitation light beams; the multi-region dichroic device has a plurality of first dichroic regions and a plurality of non-dichroic regions that are alternately arranged in stripe shapes, wherein the first dichroic regions are respectively arranged on transmission paths of the excitation light beams, wherein the excitation light beams from the excitation light source array are transmitted to the color sequence generator through the first dichroic regions of the multi-region dichroic device; the color sequence generator has a light-transmitting region and at least one second dichroic region, the light-transmitting region and the at least one second dichroic region are sequentially cut into the transmission paths of the excitation light beams, the excitation light beams penetrate through the light-transmitting region when the light-transmitting region is located on the transmission paths of the excitation light beams, and the at least one second dichroic region respectively reflects the excitation light beams to the non-dichroic regions of the multi-region dichroic device when the at least one second dichroic region is located on the transmission paths of the excitation light beams; and the excitation light beams from the color sequence generator are transmitted to the wavelength converter reflected by the non-dichroic regions of the multi-region dichroic device, the wavelength converter converts the excitation light beams into a converted light beam, the converted light beam is transmitted back to the multi-region dichroic device, the converted light beam is transmitted to the color sequence generator reflected by the multi-region dichroic device, and at least a portion of the converted light beam penetrates through the at least one second dichroic region; and wherein a light converging lens is disposed between the multi-region dichroic device and the wavelength converter and the excitation light beams reflected by the non-dichroic regions of the multi-region dichroic device pass through two sides of the light converging lens, relative to a central axis thereof, to be transmitted to the wavelength converter. the excitation light source array is configured to emit a plurality of excitation light beams; the multi-region dichroic device has a plurality of first dichroic regions and a plurality of non-dichroic regions that are alternately arranged in stripe shapes, wherein the first dichroic regions are respectively arranged on transmission paths of the excitation light beams, wherein the excitation light beams from the excitation light source array are transmitted to the color sequence generator through the first dichroic regions of the multi-region dichroic device; the color sequence generator has a light-transmitting region and at least one second dichroic region, the light-transmitting region and the at least one second dichroic region are sequentially cut into the transmission paths of the excitation light beams, the excitation light beams penetrate through the light-transmitting region when the light-transmitting region is located on the transmission paths of the excitation light beams, and the at least one second dichroic region respectively reflects the excitation light beams to the non-dichroic regions of the multi-region dichroic device when the at least one second dichroic region is located on the transmission paths of the excitation light beams; and the excitation light beams from the color sequence generator are transmitted to the wavelength converter reflected by the non-dichroic regions of the multi-region dichroic device, the wavelength converter converts the excitation light beams into a converted light beam, the converted light beam is transmitted back to the multi-region dichroic device, the converted light beam is transmitted to the color sequence generator reflected by the multi-region dichroic device, and at least a portion of the converted light beam penetrates through the at least one second dichroic region; and wherein a light converging lens is disposed between the multi-region dichroic device and the wavelength converter and the excitation light beams reflected by the non-dichroic regions of the multi-region dichroic device pass through two sides of the light converging lens, relative to a central axis thereof, to be transmitted to the wavelength converter.