A light source system includes an excitation light unit, a spectral filter unit, a scattering unit, and an excited-light unit. The excitation light unit is configured to emit excitation light. In an embodiment, the spectral filter unit reflects a portion of the excitation light to the scattering unit, the scattering unit scatters the same to generate a first light and a second light, and the spectral filter unit transmits the second light. The spectral filter unit also transmits another part of the excitation light to the excited-light unit, the excited-light unit emits excited light under the illumination thereof, and the spectral filter unit reflects the excited light, so that the spectral filter unit merges and emits the transmitted second light and the reflected excited light. The excitation light is thus split into two paths at the spectral filter unit, and finally emits light by combining excitation light and excited light.