Illumination system and projection device

An illumination system, configured to provide an illumination light beam,

• comprising:
• a light source module configured to provide a red light beam, a green light beam and a blue light beam;
• a focusing component disposed in a travel path of the red light beam, a travel path of the green light beam and a travel path of the blue light beam, the focusing component configured to focus the red light beam, the green light beam and the blue light beam to generate the illumination light beam, and the focusing component provided with an ARC layer;
• a polarization module disposed in the travel path of at least one part of the green light beam;
• wherein a polarization state of the red light beam is a linear polarization state, and after the at least one part of the green light beam passes through the polarization module, a polarization state of the at least one part of the green light beam is converted into a circular polarization state, and the at least one part of the green light beam enters the focusing component by the circular polarization state.