A projection system is provided, which includes a first light source, a second light source, a wavelength converter, a first light splitting element, and a second light splitting element. The first light source is configured to emit a first light. The second light source is configured to emit a second light. The wavelength converter is configured to convert portions or all of the second light into a third light. The third light includes a red light and a green light. A wavelength range of the first light is within a wavelength range of the red light. The first light splitting element is configured to permit the first light to pass through or to be reflected. The second light splitting element is configured for removing a portion of the first light or not removing the first light.