A light source system includes an intermediary adapter which mechanically connects a first light source module, a first irradiation module, a second light source module and a second irradiation module, a first connection mechanism which connects the first light source module and the intermediary adapter and a second connection mechanism which connects the second light source module and the intermediary adapter. The first irradiation module and the second irradiation module are interchangeably connected to the intermediary adapter in the same plane of the intermediary adapter.